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Living with Critters in Your Classroom

Teri Dannenberg and Terry Shaw, FOSS Developers
March 14, 2002 | Live Organisms

Several FOSS modules require living organisms for students to study and experience—everything from radish sprouts and ryegrass to crayfish and cockroaches. The new middle-school Diversity of Life Course, would not be complete without living organisms. They are an integral part of the learning environment, but by their very nature require more attention than the nonliving components.

Before the Critters Arrive

Prior to beginning a course that uses living organisms, you need to be prepared for their arrival. Ask yourself several questions:

  • Where will I keep them?
  • How much space do they require?
  • What kind of container do they need?
  • How much light do they need?
  • What temperature is best?
  • What do they eat?

Most of these questions are covered in the materials or the getting ready sections of the Diversity of Life teacher guide.

Here are a few things to keep in mind when ordering.

  • Most biological supply companies do not ship on Thursday or Friday to make sure that the organisms do not arrive on the weekend.
  • Plan to receive the organisms about a week before you need them in class.
  • There are usually a few fatalities after the stress of shipping. You don't want a student's discovery of a dead critter to be his or her first experience with a new organism. If you live in an area of extreme hot or cold temperatures, consider this when determining the shipping method. Consider this actual experience: a shipment of crayfish arrived on a hot Texas Saturday and sat in the mail truck until Monday. The mailman wasn't happy, neither was the teacher. The overnight shipping fees may be worth the extra cost if they save you the frustration of having to reorder.

What should I do with this roach motel now?

A student's first reaction to an insect or snail may be that they are dirty and covered with germs. This is an excellent time to discuss the difference between an organism that is found in the wild and one that is raised in captivity. The organisms that have been selected for the FOSS modules and courses are carefully chosen from reputable suppliers to prevent exposure to any potentially harmful diseases. Even so, it is a good idea to have students wash their hands after handling any organisms.

Living organisms increase the interest and enrich the experience of science for students, but a dilemma usually comes up at the end of the course, "What do I do with them now?" It is easy for us to just stop watering a plant. The soil and dead plant can be easily added to the garden or compost. But animals pose a much bigger problem. While plants and animals are all living organisms, we have a closer kinship with the animals, even the buggy sort.

Some organisms are easy to get rid of. You can usually find a student and parent willing to adopt a goldfish or guppy. You can usually be comfortable with the thought that your fish will live out their days in a glass bowl.

Insects and snails are different. After a time in your classroom, you and your students will probably begin to see these organisms as gentle and interesting to have around. But not many parents will welcome a box of creepy-crawly friends into their living room. Madagascar hissing cockroaches usually evoke an initial negative response from everyone. Some organisms, such as land snails, are also considered agricultural pests. Finding a safe and humane way to dispose of these animals is important.


Be very hesitant about giving insects to students as pets, unless you have personally talked to the parents and they are fully aware of the care and feeding of these organisms. Parents must understand how to dispose of them. The animals were not born in the wild so they should never be set free in the wild. In most areas there are severe restrictions for releasing any insect, native or not. Madagascar hissing cockroaches are certainly not native. Under no circumstances should you release them to the environment.

Have a plan for how you will get rid of organisms before you receive them so that you don't need to make a spur-of-the-moment decision. Contact the biology departments of local universities, community colleges, and high schools. Pet stores, especially those that specialize in snakes and lizards, may be interested in hissing cockroaches. If you have a local biological supply company in your state they may be willing to take them. Don't expect to be able to sell the organisms to them—they are usually just willing to take any extras off your hands. An ideal situation would be to locate a teacher in your district or area willing to maintain the organisms and share them with everyone.

If you absolutely have to get rid of them, the most painless way to euthanize them is by placing them in a closed container and putting it in the freezer for a couple of days. Then dispose of them in the garbage.

Frequently Asked Questions About FOSS Organisms


Land Snails

What if they escape?

Land snails are easy to take care of and deceptively fast. Never leave the container open or you will be finding snails in very unexpected places. If they do escape, look under shelves and behind books. They like dark places.

What should I do with them over student holidays?

They don't need to be fed and watered over holidays. If their habitat dries up, they will simply estivate until you return. Don't leave any wet food in the container that may spoil.

With a few sprays of water when you return, the snails return to their old selves. When they wake up they are very hungry; so make sure you feed them unless students will be observing their eating habits. Then it is better for them to be a bit hungry.

Will they breed?

Land snails will breed in captivity. Cover the bottom of their container with at least three centimeters of moist potting soil. Look through the bottom of the container for clusters of small, white, BB-sized eggs. The hatchlings are tiny versions of adult snails. They can escape through the holes in the lid of a six-liter container. Cover the inside lid with nylon mesh and tape in place. This will keep the babies inside.

Should I keep the males and females apart?

You can't. Snails are hermaphrodites, so it just takes two, any two. If you happen to see a love dart protruding from the neck of one of your snails, that is a sure sign they have mated.

Why does the shell feel soft and fragile?

If the shells begin to get thin and fragile, it is very easy to damage them. This is a sign that the snails are not getting enough calcium. In the wild they graze on high-calcium sources, such as limestone, cement, and dirt. To add some calcium to their diet, place a few pieces of chalk or some antacid tablets in the container. Fruit-flavored antacid tablets yield some surprising results upon egestion.

What do I do if they won't ship snails to my state?
Snails are an agricultural pest and strictly regulated in some states. Some companies cannot ship snails across state lines. Look for a biological supply company within your state or plan on collecting snails from the garden. The USDA will issue permits to use snails for educational purposes, but this can be a long process. If this is the way you have to go, start the process early. The permits can be found at the US Department of Agriculture's Animal and Plant Health Inspection Service website.


Madagascar Hissing Cockroaches

Cockroaches and a penny for comparison
Do they bite?

They have chewing mouthparts, but they are so small that they do not pose a danger to human fingers.

What about allergies?

Cockroaches do not seem to be allergic to anything. Seriously, one of the reasons we chose them is that they do not seem to cause allergic reactions, carry parasites or diseases, or bite.

While we have not found any reference to allergies associated with hissing cockroaches, some people may be allergic to molds that form in damp substrates. It is important to keep the water dish positioned so that water does not wick out into the substrate. More frequent changing of the substrate will also keep allergens in check.

Cockroaches Nothing but cockroaches
What should I do with the eggs if any appear?

The females carry the egg case inside their abdomens. You won't see them, except for a short time when the egg case is forming, and you see it protruding from her abdomen. It is then drawn back into a special cavity where the eggs mature for about 60 days. The nymphs emerge in what appears to be a live birth. Keep a little peat moss in the bottom of the tank and have something for the nymphs to crawl under or into, such as a paper towel tube.

Should I keep the males and females separate?

It is not necessary to keep them separate unless you absolutely do not want them to breed. However, the females may be carrying egg cases when you receive them. They are not aggressive and a mix of sexes and ages can be kept in the same container.

How long do they live?

Madagascar hissing cockroaches live about two years. But a healthy breeding community can be kept indefinitely.

What should I do if my school doesn't allow us to have them in the building?

There is an almost universal aversion at the mention of cockroaches. Visions of herds of huge cockroaches scurrying across the floor in the night come to mind. But remember these are not the same species as the common household or German cockroach. If you encounter resistance from administrators or other teachers, you may want to direct them to some of the websites listed at the end of this article. Assure them that the cockroaches will be secure and unable to escape. You may have to go the extra mile and over-secure them. Smear a wide line of petroleum jelly around the inside, top edge of the container. They can't stick to this. Keep the container covered with a screen or glass lid. The larger the aquarium, the less likely they are able to crawl out.

Hissing roaches are much slower moving and not nearly as prolific as other insects. They are not a health threat. If the name "roach" has bad connotations, call them something else. Some pet stores sell them as Madagascar hissing "beetles." They aren't beetles, but mothers would probably be more likely to let their children buy a beetle than a roach. It's all in the marketing.

(Note from Teri: I have to admit, I was hesitant to work with them. They reminded me of large, flying Palmetto bugs I once saw in Texas. But after a time of watching them in my office and observing students warm up to them, I did see that they are actually fascinating creatures. Don't expect them to be received with the same open, loving arms that a cute, fuzzy bunny might get, but acceptance can be gained.)

What should I do if they escape?

Catch them. They are not nearly as fast as common German cockroaches and since they lack wings they are not going to fly away. Look under things for them. Use a piece of banana for bait and have something (e.g., an egg carton or paper towel tube) for them to hide under or inside near the bait.

The best way to prevent escapees is to coat the inside top edge of the aquarium with petroleum jelly. A nice goopy border about six centimeters wide will keep adults and nymphs from climbing out. They will squeeze through any crack and climb glass or plastic, but they will not cross Vaseline.

(Note: In the three years Terry Shaw had them in his classroom, there were only two escapes. Both happened when a student thought it would be a neat idea to take them to another class and cause a commotion. To prevent this from happening in your classroom, keep them in a place in the room that you can supervise or that the students can't easily access.)

Can I feed them to my lizard?

Yes, but the exoskeleton of the adults is pretty tough. Your lizard would probably like the smaller ones better, especially just after they have molted. They are almost white for a day or so after they molt. During that time the exoskeleton is fairly soft and easier for lizards to digest.

Many people raise these cockroaches to feed to insect-eating lizards. One advantage is their ease in reproduction and the absence of offensive smells from their feces. They are not cannibalistic, so it is safe to keep the nymphs with the adults in the same container. In fact they seem to prefer crowded conditions. Like all roaches, they like to be in contact with as many surfaces as possible.

How do I humanely get rid of them?

Place the cockroaches in a container, and put the container in the freezer for a couple of days. After the cockroaches freeze, you can throw them in the garbage or use them for dissection. Madagascar hissing cockroaches are much larger than preserved grasshoppers, and internal structures are much easier to see on frozen specimens than on preserved ones. How-ever, if you use them for more than one day, you will need to keep them refrigerated between classes so they don't spoil.

If I do get them, how long will I have to keep them in the classroom for the lesson?

The activities that use the roaches take about five or six class periods. Several teachers can share the same set of cockroaches. They only need to be in each classroom that length of time. It helps for them to be visible in the classroom while the students are studying them so that they can see their behavior during the non-stressful times when they are not being handled.

Cockroach shedding Cockroach shedding




  • There are a few excellent books on the care of classroom animals. One favorite is They Don’t Have to Die: Home and Classroom Care for Small Animals, 2nd edition, by Jim Dunlap, 1996, Wordware Publishing, Inc. ISBN 1-55622-533-4. You will find practical advice, inexpensive solutions, and a bit of humor.