What is the life cycle of dermestid beetles?
The eggs of Dermestes maculatus hatch in 4 days, and then the larvae (the size of a pin head) grow through between 7-9 molts, over about 5-6 weeks, before they burrow into boring material, where they form a pupa. After 7-8 days, they emerge as a beetle. The male beetles are smaller than the females. After at least 2 months, the female beetle will lay eggs. Thus, the total lifespan is 4-5 months.
What is involved in caring for dermestid beetles?
The requirements to successfully maintain and grow a colony of dermestid beetles are relatively simple. These beetles do not bite humans, do not carry diseases, and not "invasive." If only being used for a few cleaning projects, pass them along to a friend or put them in the woods. No permits are required to raise or use beetles!
I use and recommend hard plastic totes (Serilite brand from Walmart works best!). The beetles are generally unable to climb the sides. Aquariums also make excellent containers, although it is recommended you remove the bead of silicone in the upper corners, as the beetles will climb this if this remains. Many people also use old chest freezers, which are insulated and make an ideal container for raising beetles. The beetles don't mind packing tightly, as long as there is plenty of food; get the smallest tote that will hold your cleaning project.
Add an inch of shredded paper or commercial mammal bedding (available at pet stores) to the floor of the container. (Do not use any cedar based product, such as wood shavings, as cedar is a natural insecticide!) Many folks use cotton wadding from an old mattress, as this makes an ideal substrate for the beetles to live in. Don’t be concerned if this seems like Spartan conditions; the beetles don’t need a great deal to be happy. Add numerous fist sized chunks of styrofoam, as this is the material the larvae will burrow into to grow and pupate into beetles. Keep adding styrofoam as the beetles reduce it to shreds! The beetles will create "frass", a powdery combination of their waste product and chewed up styrofoam. When the frass becomes deeper than several inches, or begins to become damp or cake, scoop half out, place in a shallow pan and place some meat on one side of the pan to lure out the beetles and larvae. Replace the beetles and pitch the excess frass.
I make and use screened lids, because you want a large amount of air circulation. This is to prevent mold growth and to keep bad bugs out of your colony. I use 1” X 1” or 1” X 2” wood material, to make a frame, and tightly staple screen door material over this frame. The frame then rests over the top of the container, and forms a tight seal to keep beetles in and pests out.
The beetles are most active in temperatures between 65 and 85 degrees. Technically, at temperatures above 80 degrees, the beetles may be able to fly, which is obviously undesirable. Consequently, it is best to keep temperatures at or below 80 degrees. However, many users of beetles report their beetles have rarely or never been observed to fly, even at higher temperatures.
The beetles prefer to work in the dark, so if the colony is not kept indoors or in a heated room, a heat lamp is not desirable as a heat source. I recommend a reptile heating pad under the container, or a non-light-emitting ceramic heating fixture. Call your local pet store for these items.
Food and water:
The beetles will feed on the dried material you want them to clean. Between cleaning jobs, meat scraps can be obtained from your local butcher, or you can uses scraps from cleaning fish or game. My beetles subsist much of the year on waste fish from our local canneries! As they prefer meats a bit dryer, freezer burned meats are also ideal to feed to the colony. The colony can go a couple weeks between feedings, if necessary. Some say dry dog food may be feed as a maintenance diet, but I have personally not had success with this method.
The beetles are watered by weekly spraying a paper towel with a spray bottle and leaving it on the bottom of the container, or spraying the specimen material. You will observe the beetles and larvae massing to drink soon after you spray.
Growth of the colony is generally controlled by the addition of food.
Pests and such:
The main potential insect pests of beetles are mites and fly larvae. Mites are prevented by keeping the colony dry. If the substrate is kept dry, mites will be extremely unlikely to survive in the colony. Proper circulation also prevents mites. Fly infestations can be prevented by insuring there are no fly eggs on the material being introduced to the colony. Feeding fresh specimen material or freezing questionable material prior to placing in the colony help insure fly larvae are not introduced to the colony.
Again, simply insuring proper circulation exists in the best insurance against accumulations of moisture and the possibility of mold.
How many beetles do I need?
For those desiring to do a single skull, or just a couple, the 300+ beetle colony may be appropriate. This size colony is intended to be a beginner colony, which would allow the colony to be grown in a few weeks to the point where a deer/bear sized skull or two could be effectively cleaned. If desiring to clean a deer/bear skull or two immediately, the 1000+ colony is recommended. This is by far the most popular size for the hunter or typical user. If considering production quantities, or beginning a small scale business, the 5000+ colony is recommended.
What about odor?
There is no getting around the fact that there may be some odor involved in using dermestid beetles. Many do not find the smell horribly offensive, but it is unique, and it can stick to clothing! Several simple things can be done to insure the odor is minimal. The beetles themselves have little or no odor; what causes an odor is the material being cleaned and the conditions in the container.
The principle offensive odor from skull cleaning is from the brains, as they are being consumed by the beetles. Brain tissue is great for the beetles, and will cause a tremendous growth spurt in the colony. However, it does stink! If odor is not an issue, you may want to consider simply leaving the brains in the skull, and letting the beetles consume this material. If odor is desired to be reduced, the brains should be removed. This is easily accomplished by whipping the brain matter with a stiff wire and flushing it out with a hose or similar process. Attempting cleaning of material with too few beetles may also contribute to odor, as the flesh will rot (and stink) faster than the beetles can effectively consume it. Keeping the frass and the colony dry will also result in insuring minimal odor.
What about shipping during freezing temperatures?
Fair question, given that I am shipping from Washington! I do several things to insure the beetles arrive in good shape. After shipping literally thousands of beetle colonies, I have had only a very few shipments where the beetles arrived dead. In these rare cases, working with the buyer determined that they suffered mortality when the shipments were left outside at the buyers end (in mailboxes, etc). In any case, if a colony suffers mortality, I will work with the buyer to resolve the matter to mutual satisfaction.
I have done testing to determine the lengths of time that my shipments can remain in differing temperatures, and have a very good understanding of what conditions they can comfortably tolerate. The packages are marked “Perishable” and “Do Not Freeze”.
The beetles are well fed and watered prior to shipment. When it is cold on either my or the buyer’s end, I place heat packs in the box with the beetles. On the day I ship, I email the buyer with a tracking number and request they notify their mail handler or post office of a pending perishable shipment, and make appropriate arrangements for pick-up or delivery.
All of these efforts combine to insure the beetles arrive in a healthy condition, hungry and ready to get to work!