Tag Archive for bugs

FAQ-Are there other pets that can live with hermit crabs?

In 2009 we introduced isopods to our crabitats.

In 2009 we introduced isopods to our crabitats.

The list of critters that can safely exist with hermit crabs is fairly short.


Isopods – beneficial tank cleaners
Springtails – beneficial tank cleaners
Food/soil mites – harmless


Fiddler Crabs/Halloween Crabs – aggressive diggers and are likely to eat molting hermit crabs.

Fiddler and Halloween crabs are aggressive diggers

Earth worms, beetles, centipedes, crickets, praying mantis, roaches: May stress each other, over populate, disrupt/harm/ kill/ eat molters. Crabs may harm /kill them. May carry/spread disease/parasites, especially with over population.

Centipedes – venomous
Millipedes – poisonous 

Snails – Hermit crabs can kill snails

Frogs/Lizards – could harm each other, different habitat needs

Fish – inappropriate water for a fish

Hermit Crab Food Foraging List

For the outdoorsy hermit crab enthusiast we have compiled a list of foods that can be collected or harvested. It’s perfect to tuck into your backpack for easy reference.


*Due to size and space limitations this is not an exhaustive list and should be cross referenced with our good/bad lists.

FAQ What foods are good and bad for hermit crabs?



Ask Milo – Brown beetles in the crabitat

Alison asks:

I have small brown beetles in my crab cage. They are not on the crabs and they are not mites. They move very fast and hide under the bowls and there are dozens and dozens of them that come out at night to eat crab food. I suspect they may have hatched from some of my high-end crab food. Any ideas for getting rid of them short of dumping the entire sand/sphagnum substrate (very large cage with six inches of substrate…weighs about 75 pounds so hard to deal with.)

Hi Alison!

It’s difficult to know what kind of bugs you are dealing with without seeing a photo. We have a couple articles that might help:
Household mites and bugs

Guide to bugs you might find in your crabitat

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/