Tag Archive for mites

Managing grain mites in the crabitat



Written by Anne Grady

Food mites, more properly called grain mites are something that can be found in any tank at any time. The first thing to understand is that they did not come from the crabs, having hermit crabs does not cause you to have food mites.

Food mites come into your home through the everyday things you buy at the grocery store. Anything that contains grain can have food mites. Oatmeal, grits, breakfast cereal, noodles, flour and rice are a few examples. In general you won’t see them and they are harmless, but that box of corn meal or pancake mix that gets left on the shelf for a few months can be the start of them multiplying and spreading through your home.

The moist, warm place that is your hermit crab tank is also a place they love and if they find it they will move in and set up house. They will begin to multiply rapidly.
You can’t totally prevent any food mites from entering your home, but using your products in a few weeks and throwing out older things will help. Placing items in your freezer will prolong their life and help kill off mites.

If you have food mites in your tank, start by taking out all food and water dishes and cleaning them very well. Remove the top ½ inch of substrate to get those you don’t see. For a week change out food every day and wash the dishes each time. Feed only dry foods during that time. Any mites you see should be removed, of course. Wipe them off the glass with a paper towel and wash décor if you think they are climbing on it.

Many react to food mites by wanting to tear down the tank and start over, but that does not address the second part of the problem, the source.

You also need to attempt to identify the source of the food mites in your home. Check things that have been on the shelf for a while. Things like flour and pancake mix you can dump just a little on the counter, make it as smooth as you can and leave it for half an hour. If you check it and the surface has been “roughed” up, it more than likely has food mites. Things like noodles and rice that won’t work that way you can freeze for 3 or 4 days to kill them if they are in there. Wash all your pantry and cupboard shelves with a good cleaner or just vinegar and water.

There is no way to completely avoid having a food mite in your home, but these methods should help you to have far fewer problems with them.


An Argument for Isolating Hermit Crabs

Hermit crab with black spot shell disease

Hermit crab with black spot shell disease

When adding newly purchased or acquired crabs to an existing colony, for the long-term health of all, we at CSJ recommend the use of an isolation tank. Placing newly purchased or adopted hermit crabs into an existing healthy colony without a quarantine period risks the unnecessary exposure of your healthy hermits to shell disease or parasites.

If you are just starting out with hermit crabs and do not have an existing colony or crabitat in place, use of the PPS Reduction Method will allow you to monitor your new crabs for 30 days and bring them slowly up to ideal environmental conditions.

The PPS Reduction Method should be used with all newly purchased crabs unless you have visually confirmed that they are from a setup with sufficient heat and humidity. This is a 30-day process, allowing sufficient time to identify signs of illness or parasites, and reduces the number of hermit crab deaths due to PPS, most of which occur within the first month but can occur up to eighteen months post-purchase. The first molt for a hermit crab in your care is the biggest hurdle in overcoming Post-Purchase Syndrome.

For adoptive hermits coming from an ideal environment, quarantine conditions should be set at recommended heat and humidity levels for an established crabitat. However we still recommend the use of shallow substrate to allow for easy visual inspection. If you prefer to allow them to dig down, plan to quarantine for 60 days instead.

If the hermit crabs are coming from an unknown environment, the PPS Reduction Method provides the needed quarantine time not only for combating PPS but also for shell disease or parasites.

Shell Disease Syndrome includes a number of exoskeleton-related bacterial infections that are easily transmitted to healthy animals. Most infections are external-only and do not affect underlying tissue unless there is cross-exposure and re-contamination while molting. (There is, however, one variant that causes the exoskeleton to fuse with underlying tissue, preventing a successful shed and resulting in death or deformity.) Crustacean shell disease is highly contagious and spreads rapidly in an artificial environment. Wild-harvested hermit crabs are warehoused in dirty, overcrowded conditions and then shipped to pet stores. One crab could expose many other crabs, particularly those made vulnerable from physical stress or injury. New crabs should always be inspected for damaged exoskeletons both at the time of purchase and prior to adding to an existing colony. When purchasing a hermit crab with visible damage, said crab should be kept in quarantine until successive molts have repaired all signs of damage or disease. At the time of writing this article, it is unclear if the bacteria that causes shell disease can survive in the substrate, so it may prove beneficial to give the hermit crab a gentle bath in ocean water before placing in the main crabitat. As a rule we do not recommend forced bathing but in this instance you do not want to risk carrying contaminated substrate into the main crabitat, thereby placing your entire colony at risk.

Mites or other parasites can hide in the shell of newly purchased hermit crabs. This is especially true of hermit crabs purchased from filthy conditions where dead hermits are present. Before selecting new hermit crabs, check them over carefully for mites or other bugs, both on the body and the shell—exterior and interior. Red mites attached to the leg joints or gills are parasitic and harmful. In rare cases there may be fly larvae inside the shell where you are unable to see it. If the store habitat is especially dirty there is a higher likelihood of phorid flies and other fly larvae being present. You may not be able to easily see mites or parasites so visual inspection does not mean it is safe to place them in the main crabitat with your healthy colony. Quarantine for 30 days and check daily for signs of mites.

If shell disease appears in an existing colony, the scenario is more complicated due to the possible contamination of substrate coupled with molters still underground. Infected crabs should be moved immediately to a quarantine tank with minimal substrate until they have molted and show no signs of infection. This may precipitate a surface molt, but that is preferable to re-infection from digging into contaminated substrate. For the main crabitat, consider replacing the substrate and sanitizing items in the tank once all molters are above ground. This may be exercising an abundance of caution, but I do believe that an episode of contaminated substrate (ten years ago) is what killed my colony of Coenobita compressus (as well as some of the other species), halting their molts and trapping them in their exoskeletons.

We do have a recipe for a hermit crab medicinal bath that may be beneficial in treating shell disease.

Hermit crab parasites

Hermit crab parasites - Drosophila larvae

Hermit crab parasites –
Drosophila larvae

Summary by Stacy Griffith
Reference: The not so lonely life of Hermit Crabs: Studies on Hermit Crab Symbionts by Jason D. Williams

Despite the name, hermit crabs are not solitary creatures. They live in large communal colonies of other hermit crabs and they are host to other species that attach to shell of the hermit crab, bore into the shell or live within the central cavity (lumen) of the shell. Discussed here are symbionts that live on, within or bore into shells worn by hermit crabs.

Land hermit crabs can harbor nine species of mites that attach to the gills.

Addition of note are polychaete worms that bore into the shells of hermit crabs. 35% of hermit crab shells in the Phillipines may contain an adult female worm. While this study focuses on marine hermit crabs, there is a possibility of a land hermit crab inhabiting one of these shells. The study does not discuss the life span of the worm once out of the water. These worms prey on hermit crab eggs within the shell.

Other stats relating to parasites of marine hermit crabs:
There are 100 species of polychaetes, 26 are endolithic (boring) which include:
Polydorids, polydora robi and polydora umanigvora which prey on host hermit crab eggs with negative impact on breeding.

An adult female worm (P. robi) feeds on eggs of the host hermit crab, eating a maximum of 70 eggs over 6 hours.
10 other invertabrates are known egg predators, including: Cnidarians (anemones and hydroids), Flat worms (stylochus zebra), Polychaetes (dipolydora common salis and lepidonotus sublevis).

185 species of parasitic isopods (family Bopyrideie) infest hermit crabs worldwide.The subfamily Athelginae attach to abdomen. The subfamily Psuedioninae attach to branchial cavity. Female isopods pierce the cuticle of the hermit crab and feed on haemolymph. This can cause parasitic castration in the hermit crab.

Land crabs are colonized by nematodes (Carson 1967), mites, Drosophila larvae, and copepods, and their exoskeletons are degraded by certain bacteria (Iversen & Beardsly 1976). [1]


  1. Grooming structure and function in some terrestrial Crustacea by Jeff G. Holmquist

Mites: Friend or Foe? The Happy Tale of the Hypoaspis Mites

written by Kerie Campbell 2005

Two months ago, during deep clean, I took my largest compressus,Houdini, out of the tank, turned him over to have a look, and a red…thing fell out of his shell. I couldn’t believe it! Mites!Huge, red mites. Houdini had a few, Fifi had some, and poor Ghidra,a pre-molt rugosus, was covered with them.

I was appalled. I inspect new crabs when I get them for mites, and have never seen any. The only explanation I have is that these mites, being a bright red color, must have snuck in on some of the perlatus – they are the same color red. I have seen these mites on my gray crabs, the brown ones and the beige ones, and still haven’t seen them on the perlatus. My eyes are just not good enough to find them on the red crabs.

Another thing that made me think these mites came from the perlatus was that they were completely unfazed by a prolonged salt water bath. Mites are supposed to float off the crabs, and if they were another type of mite, perhaps they would have. But they held on to the setae for five minutes under the water and never a one floated up. It seems to me that if they were perlatus mites, they would be used to being dragged into the ocean for long periods of time, as the perlatus love to go swimming.

It didn’t really matter where the mites came from, however; just the fact that they were present was a problem enough. My tank is 120gallons, some of the wood doesn’t fit in the oven (or can be baked safely). The mites wouldn’t come off with a regular salt bath. I’ve read post after post of people who seem to have perennial mite problems; no matter how hard and well they deep-clean, the mites come back again and again.

Then I found two of the smallest crabs, dead in the substrate. I don’t know for sure, but I suspect the mites may have either drained them dry or stressed them so badly during premolt that they couldn’t survive. Either way, I had a real problem on my hands.

I looked around on the Web for days, trying to find a solution. I found some things that looked interesting and perhaps useful, like Zoo-Med’s Mite-Off, but couldn’t get a good answer about whether or not the products would harm the crabs. I know all about insecticides, organic and chemical, but I don’t know anything about electrically-charged colloids. I don’t know what they would do to the crabs, but I couldn’t take a chance. Not this time, anyway. I figured I’d save the Mite-Off as a drastic last resort.

Then I came across something really interesting, that had occurred to me before, but I didn’t want to try first: predatory mites. I read on several sites that people use a common soil-dwelling mite predator to combat snake mites and other mites on reptiles and arachnids. The species of mite is even one I had used in my auntie’s greenhouse to kill root aphids and thrips: Hypoaspis miles (which shall be called Hypos for short from now on).

Hypoaspis mites

Hypoaspis Miles mites
Courtesy of: http://www.pbase.com/image/104370200

Finding evidence that other exotic animal owners had used Hypos successfully, I logged on to my beneficial insect supplier and ordered one bottle of 12,500.
From: http://www.entomology.wisc.edu/mbcn/kyf302.html, a description of H. miles and their commercial use:

Know Your Friends

Hypoaspis miles, A Predatory Mite

Hypoaspis miles is a soil-dwelling, predatory mite that is native to the United States. Hypoaspis feeds on fungus gnats, springtails,thrips pupae, and other small insects in the soil. The mite is 0.5mm (1/50 inch) long and light-brown in color. It inhabits the top1/2 inch layer of soil. Females lay eggs in the soil which hatch into nymphs in 1 to 2 days. Nymphs develop into adults in 5 to 6days. The life cycle takes approximately 7 to 11 days.Both nymphs and adults feed on soil-inhabiting arthropods, consuming up to 5 prey per day. They survive by feeding on algae and/or plant debris when insects aren’t available. Both males and females are present, but males are smaller and rarely seen.Hypoaspis is well adapted to moist conditions in greenhouses in a variety of growing media, but does not tolerate standing water.Hypoaspis is currently used in greenhouses for control of fungus gnats. It feeds on the young fungus gnat eggs and small larvae and is most effective when applied before fungus gnat populations become established or when populations are low. It has been successfully used in bedding plant production, potted plants, and poinsettia stock plants. The mite is formulated in a pasteurized peat mixture for commercial use. They are usually sold in 1 liter containers,which contain approximately 10,000 mites of all life stages.Containers include a shaker lid which allows for distribution over the soil surface, after which Hypoaspis will burrow into the soil.One application can establish a mite population for an entire growing season under optimal conditions. A recommended application rate from IPM Laboratories, Inc. is 1 liter container per 1000 ft2.In vegetable production, recommended applications rates for cucumbers are 4 to 8 liters per 50,000 ft2 and 10 to 12 liters per50,000 ft2 for tomatoes, with applications being made when young plants are set out in the greenhouse.

Hypoaspsis will also attack thrips pupae in the soil, but cannot be relied on for thrips control alone in a commercial greenhouse. It may, however, enchance biological control when used in conjunction with predators feeding on thrips on the foliage. In small-scale experiments this mite reduced emergence of adult thrips to about 30%of that in controls.As with all purchased natural enemies, it is important to ascertain the quality and/or presence of mites in the container. You can do this by placing a small sample on a sheet of white paper, and examining it with a 10-15X hand lens to look for the quick-moving mites. Hypoaspis moves well on soil surfaces, so it is unnecessary to apply to all surfaces. Although they will move between plants inpots, at least every second plant should be treated. Application needs to be made early enough to allow the mite to spread. They won’t move throughout an entire greenhouse from a single introduction point. Hypoaspis doesn’t survive below the top 1/2 inchof soil, so mixing mites into the growing media prior to potting isnot recommended. In addition, Hypoaspis doesn’t store very well;therefore it should be released immediately upon arrival. The mite is compatible with insect-parasitic nematodes, such as Steinernemacarpocapsae and S. feltiae, and Gnatrol, the biorational insecticide containing Bacillus thuringiensis var. israelensis.
– Raymond A. Cloyd, Purdue University

When I used Hypos in my auntie’s greenhouse, I was astonished to see them still there two years later. This is because my auntie used hydroponics, and the medium was washed and sterilized after each growing season. And yet these hardy little insects were still managing to recolonize the individual gallon pots she kept her vegetables in. It was amazing, and I was very impressed by how persistent these little helper bugs were.

Since I had experience with them, and how and on what they feed, I was not worried they’d attack my crabs. They don’t even eat adult insects their own size, just the larvae. There is absolutely no way these specialized little fellows were going to be able to hurt the crabs. Furthermore, they only live in the top half inch ofsubstrate, so they won’t bother buried molters – as I found out just today when Mothra came up from his burrow in the main tank. He still had a couple of mites on him, but I digress…

I received my mites about a week and a half later. The shipping was more expensive than the mites themselves, as the insects need to be shipped overnight. But, 12,500 mites is less than $30. With shipping, I was out $68. I think that’s a bargain for the results I got.

At first, I was very conservative with the treatment plan. The mite container can keep the mites alive for about two weeks, so you can spread out your treatment. I put a clamshell of carrier, which was wood chips (small chips, not shavings) in one ISO, two in Ghidra’sISO, and three large ones in the main tank in strategic locations.Wouldn’t you know, one of the rugosus decided to snack on the mite carrier. No big deal, it wouldn’t be insecticidal, as it’s a carrier for insects. At least Camo got some cellulose that way, and a good dose of Hypos. Later that same day, Itchy galloped through one of the bigger dishes, and I saw her scoot off to spread the love. I rubbed my hands together with glee.

By the end of the two week period, I decided it’s better, when treating a mite infestation, to do two large treatment doses over the two week period, and put as many Hypos into a tank as feasible in one shot. It seemed to work better with more Hypos added to the tank at one time.

I used Ghidra as my main subject, as I knew exactly where she was in a small tank, and she was the worst affected by the mites. She literally had dozens of them on her, poor thing, and was just miserable. Daily, I would check her while the treatment was going on. During that time, I got impatient with the Hypos’ slowness (this being the main drawback of using natural pest control in this manner) and started using a hand mister of salt water to lightly spray the mites off the crab. Held over a bowl of salt water, they would fall off, and be unable to escape, and I could drown them allin the sink when it was over. A great many adult mites died in this fashion; this is a good thing, as the Hypos won’t eat the adults,except in extremes. Daily, fewer adult mites showed up on Ghidra. Ihave checked her a total of three times in the past two weeks, as she is in premolt and I don’t want to bother her unduly, and she hasbeen mite-free all that time. After six full weeks of using Hypos in her tank, I think I can confidently say that Hypoaspis miles are without a doubt, the most efficient, cost-effective, non-labor-intensive mite treatment of them all.

So, my recommended treatment plan for mites is as follows:
1) Order Hypoaspis mites from: http://www.shopgreenmethods.com/
Put “Hypoaspis mites” in the quick search box, and the Hypos will come up, Item Number CHM125C.

Note: This website is gone. Check this list ofdistributors of beneficial insects.

Wait patiently for your order, but prepare in the meantime.

2) Daily until the order arrives, hand mist each crab over a bowl of salt water to remove any visible adult mites.

3) When the mites arrive, set up a humid place to keep the container – even in the crabitat, with the lid on, would work. I put mine on top of a bookshelf, inside a plastic garbage bag with a wet sea sponge, with the mouth of the bag hanging down over the shelf, so that air could circulate, but the humidity would stay inside.

4) Lightly dampen your substrate, should it be dry. The mites do better in damp conditions.

5) Place shells or bowls full of carrier around the tank or tanks,about half the total bottle. I would recommend sprinkling it around,but that could set up a mold problem, and would make cleaning the substrate harder in the end. If you use incandescent or heat lighting, do this during the cooler night cycle, so the mites have time to disperse.Leave the shell or dish of carrier in until then ext treatment, in about a week.

6) Continue to mist the crabs during the treatment that have visible mites, to remove them. This is much better than stressing out a crab with an unwanted, long, ineffective bath.

7) In one week, remove the old carrier dishes and replace with new ones, using up the remaining mites in the jar.

8) See number 6.

9) In one week, remove the remaining carrier.

10) Wait patiently. In about a month or so, all crabs above the substrate should be mite-free. Mites are not long-lived species, so the ones that have escaped being removed manually will die of natural causes. The Hypos are there for the eggs and larvae.

My substrate is sand, which worked well, but for people with organic substrate like coconut fiber, I think this will work better, faster,and for longer, by the very nature of the Hypos themselves.

All in all, I am very pleased with this treatment, and I recommend it very highly. Though you can shop around for Hypos from other vendors, the Green Spot is one of the least expensive, and they always send live insects. Some of the other dealers don’t always ship live ones.

Got mites? Get some more, but get the right mites for the job: Hypoaspis miles.

Main Address
The Green Spot, Ltd.93 Priest Rd.
Nottingham, NH 03290-6204 USA

Contact Means
Dept. of Bio-Ingenuity
Tel: 603 942-8925
Fax: 603 942-8932
Email: Info@GreenMethods.com
Domains: GreenMethods.com & GreenMethodsForum.com


Guide to bugs you might find in your crabitat

originally written by Jedediah


Insects have six legs and three body parts that are usually clearly visible, the head, the thorax (the breast) and the abdomen. Most of them have wings, although those might not be clearly visible, some insects can hide them in a sort of pouch on their back (like earwigs) and some insects have no wings at all. The vast majority of insects that you might find in your crabitat are beneficial, harmless or a nuisance at most. Usually you can get rid of them by doing a deep clean.

Common insects are:

Booklice aka Paperlice



Very often described as walking grains of sand, booklice are tiny and usually white to grey in colour. They are often hard to get rid of, probably because they can live in the rest of the house, too and quickly return to the crabitat where they find ideal conditions. They are harmless and even beneficial because they feed on mold and fungi.
Interesting fact: there are no male booklice, the females “clone” themselves, they are all more or less genetically identical.

2010 Booklice infestation

2010 Booklice infestation








Springtails are white, brown, green red, yellow or grey and very small, no bigger than 1/8 inch. They can hurl themselves in the air with a forklike tail they hold under their body, but they have no wings. Springtails are often found in flower pots and they need a humid atmosphere to survive, so the crabitat is ideal for them. They are beneficial because they will feed on crab poop, leftover food and other decaying material, they are excellent cleaners.
Interesting fact: Springtails are among the oldest insect species, they have been around for at least 400 million years.



Incredible skin helps springtails to keep dry underwater and always stay clean



Fruit flies or Drosophila

Drosophila- Fruit fly

Drosophila- Fruit fly

You probably know them, these are the flies that turn up whenever a piece of fruit is left for too long. The most common species is Drosophila melanogaster, around 2 mm in size, usually red eyes and a brownish colour (other species are a bit bigger or smaller, up to 4 mm). They feed on decaying fruit and breed rapidly (two weeks between generations) and can become a nuisance in the crabitat, although they are not harmful. To get rid of them, place a glass with wine, beer or fruit juice mixed with vinegar and a drop of dish liquid next to the crabitat, the flies will drown in the liquid. It’s best to stop feeding fruit for that time so that the larvae won’t find any food.
Interesting fact: Fruit flies mutate easily and you can breed really weird flies in a short time (no wings, small wings, white eyes, no eyes ect.)


Humpbacked Flies or Phorid Flies



Photos of Phorid Flies
This article states that Phorid flies do indeed infest many small invertebrates including hermit crabs: http://bugguide.net/node/view/14163

Excerpt from this page:
Other Common Names
Humpbacked Flies, Coffin Flies
Explanation of Names
Phoridae Curtis 1833
Scuttle Flies: refers to their habit of running quickly in short bursts, followed by short pauses; Coffin Flies: larvae can be a pest in mausoleums, entering coffins and feeding on the bodies inside
376 described species in 50 genera in North America (half of the fauna are Megaselia), >4,200 described species in >300 genera total(1), and many times that number undescribed(2)
Adult 1-7 mm (many 2-4 mm)
Tiny black, brown, or yellowish flies with a humped back, a low small head, and dark eyes; costal vein extends only about halfway along anterior wing margin; two strong longitudinal veins anteriorly (in costal area), and 4-5 weak veins posteriorly, not connected by cross-veins; hind femora enlarged and flattened, and hind legs long; antennae appear 1-segmented
The way of life of most species is unknown. A few common, synanthropic species, especially Megaselia scalaris, Dohrniphora cornuta, Megaselia rufipes, and Puliciphora borinquenensis, live in almost any type of decaying organic material. Larvae of D. cornuta often build up to huge populations when sewer pipes break and nutrient-rich water soaks into the soil; adults emerge in swarms through drain pipes in affected houses. The most commonly noticed species of phorid is M. scalaris, which is found in a number of filth-fly situations, and also infests nearly every type of invertebrate and small vertebrate cultures, such as insect zoos, tarantulas, lizards, snakes, hermit crabs, etc.
Most species, however, are probably specialized scavengers, predators, parasitoids, and even true parasites. Many Megaselia species are found in fungi, some feeding on the fungus (including a few commercially important pests), others probably feeding on sciarid larvae. Many species are found in buried carrion, away from competition from blow flies and other agressive species. One such species, the coffin fly, is found commonly on buried human bodies. Small invertebrate carrion, such as snails, slug, and dead insects, are also breeding sites for phorids. Species of the genus Anevrina are found in the burrows of mammals, probably as scavengers.
Many species are associated with ants, as commensals in ant nests or as parasitoids. The largest group of ant-parasitoids, Apocephalus, are known as ant-decapitating flies because they develop inside the ant’s head, and some species cause the ant’s head to fall off, sometimes before the rest of the body stops moving. Most North American Apocephalus attack ants in the genera Camponotus and Pheidole, but other hosts are used here and elsewhere. Another ant-parasitoid genus is Pseudacteon, whose South American species are being used in attempts to biologically control imported fire ants (since the native Pseudacteon are not doing the job!).
Other parasitoid genera attack millipedes (phorid genus Myriophora), fireflies and cantharid beetles (some Apocephalus), bees (some other Apocephalus), scale insects, beetles, and probably many other hosts we do not know about.
Some phorids have wingless or short-winged females. Some of these are commensals or parasitoids associated with ants, others are scavengers that are apparently not associated with ants.
-Brian Brown”

Controlling phorid flies infestation

They look very much like fruit flies, but if you take a closer look, you can see a hump. Apart from that, they can be recognized by the way they run around: very fast, always stopping after a short distance and very reluctant to fly. Humpbacked flies are the only insects that have been found in crabitats that can be harmfull to the crabs, at least I haven’t heard of any other. The adults and larvae can feed on almost anything including flesh, so if a crab has an open wound the larvae are able to get into the wound and eat the crab from the inside out. Some species are able to lay their eggs into healthy animals, but those are parasites of a certain species and as far as I know, no phorid fly preys on land hermit crabs specifically. To get rid of them, do a deep clean, bake or boil everything, bathe the crabs and I recommend keeping the crabs in an ISO tank that’s easy to clean for six weeks to make sure there are no eggs or larvae left. Clean the ISO every week (change substrate and hiding places, boil or bake the hiding places you want to use again) and make sure the food doesn’t spoil.

Interesting fact: Phorid flies have been known to survive by eating shoe polish – you somehow have to admire a bug that’s so adaptive

http://ohioline.osu.edu/hyg-fact/2000/2144.html (dead link)


Fungus gnats

Fungus gnat

Fungus gnat

Fungus gnats are small (2,5 mm), black flies. Both the adults and the larvae feed on decaying and living plant matter, the adults eat pollen, too, and they are harmless to the crabs, but can become a pest when they multiply too much. To get rid of them, you can use yellow sticky traps. Those are sticky on both sides and can be attached to the lid of the crabitat where the crabs cannot reach them.


Silverfish and Firebrats

Silverfish Firebrat

Silverfish Firebrat

Those are rarely found in crabitats, but I will include them anyway. Silverfish are often found in bathrooms, firebrats need a high temperature to breed and are sometimes found in bakeries and other warm places. Both look similar, 1/3 to ¾ inches long and carrot shaped without wings. Silverfish are silver in colour and really look a bit like fish. Firebrats are hairy and often have dark grey stripes on their body. Both feed on almost anything at all, including cereals, fish food ect. They are harmless and won’t breed in the crabitat because it’s too humid and too cool for the firebrats and probably too hot for the silverfish, so they will disappear eventually. They mostly get into crabitats by chance.
Interesting fact: Both can survive and even thrive on a steady diet of wallpaper, tissue paper or similar things. Like springtails, they have been around for a very long time.




There are more insects that can be found in your crabitat, especially small flies and other tiny insects living in the soil, but those are the species that people have found very often and that were positively identified. If you find something else, try to take a picture of make a drawing so that the bug can be identified.


Arachnids are such bugs as spiders, scorpions, mites and other bugs related to spiders. They have two body parts, the thorax and the abdomen, no wings or antenna and eight legs.


There are thousands of species of mites and it’s extremely hard to identify them. They come in all colours (white, grey, black, brown, bright red ect.) and many sizes. Only comparatively few species are harmful for the crabs. The rule of thumb is: if you find them in the food dish or the rest of the crabitat, they are probably harmless. If you find them on the crab, especially on the joints, the abdomen or the mouthparts, they are predatory and harmfull. A deep clean will get rid of the harmless mites, for the predatory ones you will need to bathe the crabs in salt water or you might even need to pick off the mites because they have claws on their legs to hold onto their prey.

Interesting fact: Some mites feed on pollen and hitch rides with hummingbirds, racing up the beak and then down again into a new flower. Others hitch rides with flying insects to reach new plants and some not only hitch a ride, but also suck the haemolymph (insect blood) on the insect that’s carrying them. Many species change their dietary habits depending on their age.

Click on the links at the bottom to see pictures of mites hitching rides with insects:


Other mite pictures:

Bookscorpion or Pseudoscorpions



A rare guest in crabitats that sometimes comes with moss or leaf litter is the bookscorpion. They look like tiny (1-4 mm) scorpions, but have no tail and are absolutely harmless unless you are a springtail or a fruit fly.

Interesting fact: One species, Chelifer cancroides, does live in books and this species gave the whole order its name. They dance with each other during mating and they build a small nest from grains of sand, moss and silk. The females produce a nourishing substance for their babies, so in a sense they nurse their babies.


Other bugs you might find




Woodlice, also called pillbugs, sowbugs or rolypolys, are the only crustaceans that live permanently on land without any contact to water. They need a humid atmosphere to breathe, that’s why they are sometimes found in crabitats. Woodlice are harmless and feed on decaying plant matter. They are often used as tank cleaners with reptiles, phasmids and other animals.

http://www.geocities.com/CapeCanaveral/Hangar/7649/wlice.htm (DEAD LINK)


Millipedes and Centipedes





Both belong to the Subphylum Myrapodia (this means “numerous feet”) of the Phyllum Arthropoda (“joint-legged”), which insects, arachnids and crustaceans belong to, too. Millipedes (“with a thousand feet”) have two legs on either side per body segment, centipedes (“with a hundred feet”) only one. They sometimes turn up in crabitats and come from moss, leaf litter or with live plants. Millipedes are vegetarians that feed on decaying plant matter, centipedes are predators. The centipedes you might find in your crabitat are very small and are no danger to the crabs.

Interesting fact: Millipede males of some species can breed only after every second molt.


Bugs that help getting rid of other bugs

You can purchase predatory mites or insects that will feed on some bugs in your crabitat and then die when they find no more prey. This is a efficient and absolutely crab-safe method to get rid of bugs, without stressing the crabs by doing deep cleans ect.

Here’s one website that offers such bugs:

Varieties of Household Mites


FAQ Varities of household mite – Booklice

Originally written by Vanessa Pike-Russell-Updated by Stacy Griffith

Common Name/Scientific Name

Dust Mites-House Dust Mite Dermatophagoides sp.

Grain Mites-Grain Mite Acarus siro L

House Mouse Mite-Liponyssoides sanuineus (Hirst)

Follicle Mite-Demodex folliculorum (Simon)

Itch or Scabies Mite-Sarcoptes scabiei hominis (Hering)
Mold Mite-Tyrophagus putrescentiae (Schrank)

Dust Mites – House Dust Mite Dermatophagoides sp.

“Dust mites are microscopic, small enough to live inside the weave and fibers of your clothing, bedding carpet and such. They don’t actually bite they are waaay to small .. they actually live on the skins flakes we shed. When people have problems with dust mites it is because they are actually allergic to the proteins in their saliva and excrement! So there is precious little on a hermit crab to attract or sustain a dust mite.

Grain Mites – Grain Mite Acarus siro L.

“Stored grain is subject to insect infestation and deterioration from molds and bacteria. High grain temperatures and moisture, along with dockage and broken kernels, provide conditions that accelerate mold and insect development. Many grain insects are good fliers and move to newly stored grain from fields and from infested grain bins. Insects can reach a high population size in unchecked grain bins, in sub floors or aeration ducts in bins, in equipment used to move grain, or in discarded refuse grain. These areas must be kept free of insects to reduce migration to newly harvested grain.

Grain insects move within the grain mass at a rate that is determined by the and grain temperature. During the summer and fall, insect infestations are usually on the surface of the grain. In cold weather, insects congregate at the center and lower portions of the grain and may escape detection until high population numbers are reached.” (Vera Krischik, USDA FGIS and the Institute of Ecosystem Studies Wendell Burkholder, USDA ARS and the University of Wisconsin)

Grain Mite Infestation: Prevention and Control

This site has information about the Grain Mite, which feeds on food similar to that which we offer our hermit crabs i.e., Wheat Germ (FMR Treat), Soyabean Meal(FMR Food), Rolled Oats, etc.
“Mite populations can explode when they feed on wheat germ, yeast, cheese, powdered milk, flour, or grain. In finely ground commodities such as flour and powdered milk, infestations are confined to the surface layer. Whole or cracked grains and nuts may be infested throughout.” (Linda J. Mason and John Obermeyer, Department of Entomology

Grain and Mold Mites

These mites can be found in a wide variety of stored products and food and can cause mild dermatitis known as “grocer’s itch.” Heavy infestations have a sweet or minty odor. A coating of “mite dust,” molted skins of the mites, covers the infested grain or cheese. Sometimes the surface of infested materials appears to move due to large numbers of mites. These mites favor damp areas. They do not bite humans. (William F. Lyon W. Calvin Welbourn

Common Mite Species

Index of Mites for Identification
A list or index to many types of mites that are attracted to grain and will infest areas where foods like wheat germ, soybean meal, rice meal, flour, oats and cereals exist.

Are the mites/bugs in your tank harmful?

Not all bugs are lethal to your hermit crabs. Check out our guide to bugs in the crabitat before you panic.


A crabarium that is infested with mites and other pests cause hermit crabs to become stressed, lose limbs and die. It is important that you do not use chemicals that could be harmful to hermit crabs in ridding their home and yours of pests.

Hermit crabs are very sensitive to the presence of chemicals and they may suffocate if pesticides are sprayed close by. Keep the tank covered and wherever possible, find a natural alternative in cleaning products.

If you DO have mites, this is one way that I have found to get rid of them:

The substrate and crabarium items boiled and dried, your tank cleaned out with vinegar paying special attention to the silicone inside, and give your hermit crabs a dechlorinated ocean/sea water bath until they are free of these pests. The mites should float to the surface during the baths. As Jenn notes, mites are often attracted to wood and plants so make sure you rid the crabarium of wood that attracts mites and other bugs until the crabitat is pest free.

You may need to use a magnifying glass to zoom in, make sure you have rid your tank of these pests, and keep a screen lid on your tank under your glass/Plexiglas lid to keep the flies, mites and bugs away from your crabs and their food. Always remove fresh fruits the morning after to keep your hermit crabs safe from infestation.

A crabarium that is infested with mites and other pests cause hermit crabs to become stressed,lose limbs and die. It is important that you do not use chemicals that could be harmful to hermit crabs in ridding their home and yours of pests. This includes any chemicals or formulas that are sold to kill mites due to hermit crabs belonging to the arthropod phylum.

Hermit crabs are very sensitive to the presence of chemicals and they may suffocate if pesticides are sprayed close by. Keep the tank covered and wherever possible, find a natural alternative in cleaning products.

Hermit Crabs are known to rarely mate in captivity, so there is an extremely slim chance of breeding your hermit crabs. Some hermit crab owners have been mistaking in thinking the eggs of a larvae fly were tiny hermit crab eggs. If you see anything other than hermit crabs in your tank, there is highly probable that it is a PEST and should be removed as soon as possible. If you see any sign of mites, eggs or other pest it is important that you remove it quickly.

The only way it could be hermit crab eggs is if you have received a hermit crab straight from the wild that is gravid, or laden with eggs. Hermit Crabs with eggs are NOT supposed to be harvested at all, so this is very rare. At present only two scientists (that I am aware of) have successfully raised hermit crabs from egg stage to Juvenile stage in a lab. It is a very difficult process and without the set-up, tools and skills it is very unlikely that it could be recreated in a home setting. But on extreme rare occasions when the crabber has had optimal tank conditions, a hermit crab has become laden with eggs. But unfortunately have not been able to raise the zoea through the metamorphosis stages.

Biological solution to mites

Let predatory mites get rid of your parasitic mites. Read about Hypoaspis Mites

A note from CLD on Mites and Lost Limbs:

****Note: Whereas during CrabLover Don’s time he had a wealth of information, through further research and experience it has some of the information has become outdated.
From: CRABLOVER DON Date: Fri Mar 17, 2000 12:20 pm
Subject: Clearing up some MYTHS…..MYTH #1…… DEATH SENTENCES

Okay, let’s do a little ‘BASIC’ hermie FACT application… starting with the biggest MYTH out there… the death sentence due to the loss of a claw (or even two)… I hope you won’t mention this to any of my guys… as they can prove you wrong…VERY QUICKLY!!

Some guys may be a little ‘challenged’ at first, but they soon adapt to the situation and do quite nicely until that missing appendage is regenerated!

Hermit Crabs CAN live quite well missing one or even both of their “claws’. Why do I know this? Because I have a dozen or more fellas with these ‘challenges’ LIVING among my two hundred plus crabs. The fact is these claws do have certain functions… the larger (left)’claw’ is used basically for defense and climbing, while the smaller (right) one is used for eating and climbing. At first i did ‘handfeed’ some of the guys missing both claws, but these guys are amazing in finding alternative ways to eat and drink… IF the crab IS HEALTHY otherwise they usually survive!

It is easy to pass death off on the fact that you are not sure what the *real* problem is! If a crab starts losing any appendage, there is usually a problem… in most cases it is because of a stress related factor. These reasons are usually not from ‘attacks’ as I hear so often, but because of under-lying problems such as bacterial growths ; poor control of temperature and humidity levels ; dehydration ; poor ‘housekeeping’ ; exposure to odors, housekeeping sprays, ‘fumes’; a molt gone bad…etc.

What is necessary, to prevent further problems/deaths, is to locate and DETERMINE what PROBLEM is causing and creating this stress. Ninety-nine percent of the time there is an underlying cause… At the first sign of a crab losing a leg or claw, IMMEDIATE attention should be paid to the situation and to be as prompt as possible in seeking EXPERT advice! Just use good ‘common sense’ and seek assistance BEFORE the situation gets out of hand! … Many deaths can be avoided, but only IF the underlying factors can be corrected and resolved. It is often better to correct the situation and get things ‘under control, before bringing any new little ones into a problem situation…

From some personal experiences, observations and a great deal of experience in trying to help others; but, more so from the bottom of my heart… take a few minutes and stop, reason and think! It really makes for much Happier Crabbing for all!

Happy Crabbing!

P.S.: I urge each of you crabbers old or new to think about investing in a good crab care book… there are a few better than others, many are very ‘out of date’ but have some good information… One recently published one I highly recommend is:HERMIT CRABS: A Complete Pet Owner’s Manual…a “Barron book”… written by Sue Fox. Both Amazon.com and Barnes and Nobles offer a discount on online orders… in the store it costs around $6.95. Sue has some great information in there plus the pixs are fantastic!

(Cralover Don AKA Don Drenning) bear in mind most of these methods are no longer current practice.

The books mentioned above are also outdated and no longer practiced. Majority of the books sold on the market are outdated, and only provide very basic care information.


William F. Lyon, W. Calvin Welbourn. Mites Annoying Humans
HYG-2101-95. URL : http://ohioline.osu.edu/hyg-fact/2000/2101.html
Linda J. Mason and John Obermeyer, Department of Entomology.
URL: http://www.agcom.purdue.edu/AgCom/Pubs/GQ/GQ-13.html
Vera Krischik, USDA FGIS and the Institute of Ecosystem Studies
Wendell Burkholder, USDA ARS and the University of Wisconsin

URL: http://ipmworld.umn.edu/chapters/krischik/index.html
Insect Publications Oklahoma Cooperative Extension Service
Home and Garden Insects
URL: http://agweb.okstate.edu/pearl/insects/home/