Dermestid beetles are a low-cost, low-maintenance solution to frequent Dubia roach enclosure cleanings. But while they can save time and effort, they aren’t themselves maintenance free. They do need at least some attention. While it’s possible to add Dermestid cleaner crews to a Dubia colony and forget about them, we recommend making sure you meet their basic needs.
This article describes how to do that. It provides instructions for adding Dermestid beetles and other cleaner insects to Dubia roach colonies. It’s focus is maintaining the cleaners (beetles & larvae) so they function as intended. The first section has basic step-by-step instructions. The second section provides in-depth information to help maintain a healthy relationship between Dubia roaches and Dermestid beetles.
NOTE: This information is based entirely on our experience and research. Because every situation is unique, your experience may vary. These instructions are intentionally broad, but they aren’t universal. Climate, food availability, light & dark cycles, and other factors can affect insect behavior, and you may need to make adjustments to get the results you want.
Basic instructions for Dermestid cleaner crews
1. Check the water supply
Dermestid beetles (and their larvae) don’t need much food, but they do require frequent water. Absent food, we suggest watering them daily. You can extend this time to weekly by providing access to food.
In a Dubia colony, the regular and reliable moisture you give your roaches should also meet the needs of the beetles. Water crystals, sponges, and paper towels are all great ways to water you Dermestids and Dubia because Dermestids do not eat vegetation. They can probably extract water from high water content vegetables, but you probably shouldn’t count on that.
Dermestid beetles and larvae also get moisture from the dead roaches they eat. This alone may satisfy their water needs. However, we recommend providing supplemental water at least until they become established in the colony. Relying on food for their moisture needs is risky. This is especially true in the beginning, before they are established.
After they become established, if they have regular food (which they will), and access to the water you provide for your roaches (which they will), you probably don’t need to worry about water. To test this, offer them occasional water to see how they respond. You can spray a clean paper towel or sponge with water and set it on a flat, leak-proof lid of some sort. If they’re not interested, you’re all set.
2. Add them to your colony
When your beetles and larvae arrive, simply add them to your roach colony. You can empty the entire contents of the container into your roach bin, or you can separate the insects from the frass and just add the insects. It’s up to you.
They will seek food and shelter as they acclimate to their new living space. There is no need to give them supplemental food now. They will arrive fully fed. “Primed”, as they say. Unless there are extraordinary circumstances (like high temperatures or a shipping delay), they don’t require any immediate action or care on your part. They should be OK for at least a week.
They may appreciate some water though. Presumably there is already water in the roach bin. If not, add a damp paper towel to the enclosure, a damp sponge, hydrated water crystals, or some other watering method for the Dermestids. Dermestid beetles and larvae are better climbers than Dubia roaches, so if the roaches can reach water, the Dermestids can too.
3. Check food and shelter
Food: If you have a small Dubia colony where roaches die so infrequently that the Dermestids may go more than a week without food, consider adding something to tide them over until the colony grows and more roach carcasses become available. You can feed them dry cat or dog food, a hide chew toy, or a chicken (or other) bone with a little meat or cartilage on it.
Shelter: Dermestid larvae like to burrow before they pupate. This protect them from predation. While Dubia roaches don’t generally harass Dermestid pupae, you may want to give them some burrowing material anyway. This behavior is innate, and supporting it may increase their health. A small block of Styrofoam or a piece of corrugated cardboard will work. Just drop it in and they’ll find it. The burrowing behavior will use up the material over time, so replace it with new material when the old one is no longer useful.
4. Control the population
Keep an eye on your Dermestid population and take action when their number falls outside what you need to keep up with cleaning. Generally, this means doing nothing when the population level is OK, providing food when it drops too low, and restricting food when it’s too high.
All things equal, your rate of roach die-off will remain constant and the Dermestid population will self-regulate in response. This means you will want the Dermestid population to grow (and not decline) after buying a cleaner crew Kit. To learn how to do this, see below.
More details on maintaining dermestid beetles (and others) as cleaners
This section has in-depth details about managing a colony of Dermestid beetle and larvae cleaner crews inside a Dubia roach colony. It also explains how to care for Dermestid beetles and how to manage Dermestid cleaners in combination with other cleaner species.
Notes on feeding
When providing supplemental food to Dermestids, make sure it’s dry enough that it doesn’t overtly rot or become rancid. Dermestid beetles and larvae will eat rotting meat, but they prefer flesh with a moisture content between 15% and 40%. They may find foul, fluid-oozing meat less palatable than meat that is drier. And in the context of Dubia roaches and cleaner crews, wet meat runs counter to their intended purpose. Dermestid beetles exist in the colony to reduce moisture and bacteria, not increase it. They shouldn’t create the problems they’re meant to solve.
To this end, allow meat time to dry before placing it in the enclosure. You can wrap it with a paper towel and squeeze to remove excess moisture. You can also place it in a warm spot under a fan to keep flies away and speed drying. However, if you do this, take care to avoid flies. Flies aren’t just a nuisance. You will end up with maggots if flies find the meat, and in addition to raising Dermestid beetles and Dubia roaches, you will also be raising flies.
Meat also dries out in a freezer or refrigerator. This eliminates the fly problem but it takes a lot longer.
Make sure the muscle of any meat you dry is not so thick that it rots instead of drying over the course of a few days. Freezer burned meat often works well as Dermestidae food. NOTE: Freezing meat slows the development of fly eggs (external link) that may have been laid on it, but it may not kill them.
However you prepare the meat, the bottom line is that if it’s muscle, Dermestid beetles and larvae will eat it. However, in this context we’re just concerned with keeping them alive until they have enough dead roaches to eat. We’re not aiming for an optimum diet. Generally, you should feed them supplementally until there is at least one dead roach per week to sustain them. This is a very rough estimate. Consider providing food for the Dermestids if your Dubia colony produces less than this. One dead roach per week is probably enough to support at least some Dermestid life in the colony. All things equal, more dead roaches will stimulate Dermestid population growth. Again, these are rough estimates. Your mileage may vary.
Be aware that commercially dried or processed meats are not ideal for Dermestid breeding. This matters if you’re supplementing their diet with meat to promote population growth. Try providing fresh meat if you’re trying to build the Dermestid population and you find it’s not happening. Dangers to Dubia roach health aside, wet meat should be just moist enough for the beetles to lay their eggs and for the eggs to incubate and hatch. This happens in three to four days on average, so the meat needs to remain moist at least that long.
However, “moist” does not mean “wet”. Translating the moisture level necessary for egg laying from “between 15% and 40%” to something the average person can gauge is difficult. It seems to come out somewhere between “wetter than beef jerky” and “drier than a piece of fresh, raw chicken”. You can experiment to see what works best in your location, as the moisture level necessary for reproduction is probably related to humidity as well as temperature within the colony.
What we’ve found is that the right moisture level is what you might get from taking a raw chicken wing, wrapping it in a paper towel, squeezing out the moisture, then setting it aside in the refrigerator for a day or two. The visual we’re going for is dry and firm on the outside but perhaps still a little moist and flexible on the inside.
For reference, the way it works in the wild (external link) is that dead animal carcasses that have reached a certain dryness and state of decomposition attract Dermestid beetles. This is usually about 9 days after death, although this may vary depending on environmental conditions. Following the scent of a body that has reached a certain decomposition stage, males fly in and settle down. They will proceed to eat for a few days. When conditions are right, they survive and thrive, and their pheromones accumulate to a point that female beetles take notice and begin arriving. Mating starts at that point, and females begin laying eggs soon after. Three to four days later, newborn Dermestid larvae emerge and begin feeding. They grow rapidly, and when they become adults, they will repeat this cycle.
One lesson in this is that Dermestid beetles aren’t strongly attracted to fresh, wet meat. It needs to be dry, but not too dry for egg incubation. Larvae, on the other hand, are fine consuming drier meat as that is usually what’s left by the time they hatch and begin feeding on a carcass in the wild. If you’re providing your Dermestids with supplemental food for population growth, cover the meat with a moist paper towel if you find that it tends to dry out and the population is not increasing as fast as you’d like. A little moisture increases humidity and slows evaporation, and this is often enough to increase Dermestid beetle reproduction.
Be very careful if you’re doing all this inside a Dubia roach colony. Place the meat on some sort of lid or dish so moisture doesn’t transfer to frass, harborage, or elsewhere in the enclosure. Try finding the minimum moisture necessary for Dermestid reproduction to help preserve the health of your Dubia. Minimizing moisture lessens the chance harm will come to your roaches from moisture accumulation or bacterial overgrowth.
Dermestids in combination with lesser mealworms
Lesser mealworms can also serve as cleaners, either alone or in combination with Dermestid beetles. Like Dermestidae, they also seek food in the Dubia colony. However, unlike Dermestidae, they prefer vegetation to meat. They also eat roach feces, or frass. This means you don’t need to feed them, but it also means they may find your roach chow. While the worms themselves prefer to live and eat in frass, they will eat roach chow when they find it. They may also breed in it. While this is great for the mealworms, it’s not ideal for the roaches.
You can help manage this issue by keeping food and water in a dish and not strewn on the floor. Scattered food encourages rapid mealworm population growth while localized food does not. Or if it does, it’s to a lesser degree. Using a food dish also makes it easy to see if the beetles have gotten into the roach chow. Cleanup is much easier too. If you want your lesser mealworm population to grow fast, put food on the floor or clean out the colony’s food dish less often. If you want it to grow slowly or maintain the current population, put food in a dish and clean it often. Again, these are general rules and rough estimates.
Placing the Dubia’s food in a bowl won’t prevent the beetles from reaching it, and it’s not intended to. The goal is to slow them down, not stop them entirely. Limiting their access to food is a strategy to keep their population in check, not eliminate them entirely.
An issue that occasionally comes up with lesser mealworms is their fast growth. Females can lay 2,000 eggs in their lifetime and eggs can hatch in just a few days. This means their population can grow faster than Dermestid beetles. When food is strewn about on the floor, it is difficult to know if the beetles are eating your roach chow until they’ve grown quite numerous. This is especially true if there’s a lot of frass in the bin. While prevention is usually just a matter of using a bowl and clearing out old food as mentioned above, there are a few things you can do if you discover an unwanted population increase and/or beetles and larvae in your roach food.
First, know that they lay their eggs in moist locations. They prefer the carcasses of dead roaches because they are a nurturing environment for beetle eggs. The carcass also becomes food for the larvae after hatching. If there aren’t enough dead roach carcasses, beetles may lay eggs in moist food like fruits and vegetables. They may also lay eggs in moist foods that contain animal products, like kibble.
This may not be a big deal at first. In fact, it may even be good for the roaches because insect eggs provide extra nutrition. This is how they get much of their protein in the wild (pdf) (external link). However, it may become problematic if the eggs overwhelm the colony’s ability to clear them.
This is one reason why we think lesser mealworms work well in combination with Dermestid beetles and larvae. Dermestids eat dead roaches. This slows lesser mealworm reproduction. Lesser mealworms grow rapidly, so the reduction promotes balance and is therefore beneficial.
Dealing with overgrowth
To avoid overgrowth, or deal with it once it occurs, consider the following: either (a) feed your roaches less food and/or less often so all the food is eaten rather than sitting idle where it will become a breeding ground for mealworms, or (b) clean the bin to reduce the mealworm population. One or the other – either alone or in combination – are effective control methods. And, each becomes easier when roach chow is kept in a bowl rather than scattered about the bin.
You can tell when an insect has gotten into your roach chow. It will turn into a fine powder as they consume it. Larvae burrow because they hate light. As a result, they consume roach chow from the bottom up. Stick a finger in a dish of roach chow and swirl it around. If the bottom is white and chalky, it means something other than the roaches are eating it. At this point it should be discarded. When beetles get into fruits or vegetables, you will see the larvae on or under the vegetation. At this point it will likely have become rotten and smelly as it was liquefied by hungry larvae. You may also notice that your roaches begin to avoid infested food. Again, this means it’s time for a change. Throw that food away if you do not want the cleaner crew population to increase.
Seeking population balance
In managing a roach colony with Dermestid beetle cleaners – either alone or with other cleaner species – the goal is balance. You might want to shoot for as many Dermestids as it takes to clear the colony of decaying animal matter, and all the lesser mealworms it takes to clean up the frass. However, you don’t want enough of either to overwhelm the roaches. You don’t want them competing with the roaches for food.
Fortunately, each of these species tend to live more or less symbiotically as their needs balance. However, the two beetle species tend to balance a little differently. There are different issues to watch out for with each of them. With Dermestids, the tendency is on the side of too few. They can be a little tricky to get established, and they may tend to die out if conditions aren’t adequate.
Lesser mealworms, on the other hand, are prolific and tend toward large numbers. They will eat whatever you feed your roaches, so unlike Dermestidae, their food supply is more plentiful and reliable. Fortunately, the difference between proper population balance and “overgrowth” is significant time and a very large number of larvae and beetles. This means preventing overgrowth is relatively easy. Dealing with overgrowth once it occurs is relatively easy too. Clean out the bin to reduce the mealworm population and use a food dish to slow population growth. Easy.
NOTE: To get a general sense of what’s going on with the balance of cleaner crews to roaches, keep an eye out for an accumulation of moist, dead roaches and the smell of ammonia. This may happen if you have too few Dermestids. If there are too few lesser mealworms, the frass may become moist and smell moldy from decaying plant matter. If there are too many, they will be eating the food intended for your roaches.
Clean the bin or adjust the appropriate insect population if you see any of these signs. Remember that the “sweet spot” where there are neither too few nor too many cleaner crews is a range, and it’s large. It may take weeks or months before the balance is significantly disrupted. Also remember that regardless of their numbers, neither Dermestid beetles nor lesser mealworms will harm your roaches directly. Simply reduce the numbers and/or try our food recommendations if there are too many.
Related reading: Identify and resolve problems in Dubia roach colonies »
Useful Dermestidae information
You may find the following information useful as you manage your roach colony with cleaners. It can be used to prevent or resolve issues.
- The ideal Dermestid beetle breeding temperature is about 80ºF. They will, however, breed at room temperature. Other cleaner species breed fast at this temperature too. Because Dubia roaches are usually kept at slightly higher temperatures, Dermestidae reproduction will slow slightly from its full potential. Store them at 80ºF or slightly lower to restore their full breeding capacity.
- Females reportedly lay between 100 and 200 eggs. They prefer to do so in the folds of slightly moist flesh. Eggs hatch in just a few days, the breeding cycle is around six weeks, and the life cycle is between five and six months. Once pregnant, females remain gravid throughout their entire adult lives.
- Dermestid larvae seek shelter before they pupate. They burrow into soft material as mature larvae and emerge from the holes as beetles. While Dubia roaches will not harass pupating insects, it’s possible that other Dermestid beetles and larvae, or other cleaner insects might. Adding a piece of Styrofoam or corrugated cardboard to the colony for them to burrow into may increase Dermestidae pupation success. The result is more beetles, more eggs, and a larger Dermestid population generally.
- Dermestid reproduction is slower than lesser mealworms, but they eat different foods so managing them separately is doable. As with any insect, population depends on environment and food supply. As a general rule, the supply of dead roaches determines the Dermestid population. The amount of frass and vegetation determines the lesser mealworm population. Adjust either of these to suit your needs.
- Dermestid beetles can fly at temperatures above about 85-90ºF, but not below. A lid on a typical plastic bin is usually enough to keep most of them contained, but escape may be inevitable when they’re kept with Dubia roaches. You should assume that and anticipate it. Neither the beetles or their larvae can climb smooth surfaces like glass or slick plastic. Lesser mealworm beetles, we’re pleased to say, cannot fly and are poor climbers.
- Dermestidae are attracted to rotting meat. The beetles will eat what they can and also lay eggs if the meat is moist enough, but not too moist. It takes three to four days for the eggs to hatch, so make sure the food supply is greater than what they eat in three days if you want to breed Dermestids.
- Dermestid beetles will not lay eggs if their food is too dry. Look here first if you want their population to increase but it’s not happening. This means you may have to balance the potential for rotting meat nastiness with your desire for a safe and healthy B. dubia colony. Because breeding a population of Dermestids of any decent size requires feeding them actual meat and not just dog or cat food, we recommend breeding them in a separate enclosure. Maintaining a small cleaner population inside a Dubia roach colony is easy, but if you really want to grow their numbers beyond what’s required to clean up after your roaches, you will need to deal with moisture at best, and the smell of rotten meat at worst.
- The smell of ammonia is always a danger sign in a Dubia colony. It means moisture and/or unprocessed roach carcasses have accumulated and the environment has become unhealthy. We suggest cleaning the bin without delay at this point. Dermestid beetles live inside dead animals and can probably handle foul conditions, but tropical roaches like B. dubia cannot. Don’t forget that it is a Dubia colony and the cleaner crews exist to make the environment more healthy for the roaches, not less.
- Dermestes maculatus does not prefer skin. They aren’t generalist feeders like other Dermestidae. This means they work well with other cleaner species as resource competition is reduced. It also means they require a steady supply of dead roaches (or supplemental food) to survive.
- The lifespan of Dermestes maculatus (aka: the hide beetle) is 21-31 weeks (5-7 weeks to reach adulthood + 16-24 week adult beetle longevity.
- All cleaner crew insects can cause problems in your home if they escape. We’ve never had an issue, but that doesn’t mean there’s no risk. If there is any question about their suitability for your location or situation, or your ability to keep the insects safely confined to their enclosure, you should research the matter further before making a final decision.
- Dermestid beetles and larvae can cause damage to timber, cork, plaster, linen, and cotton, when they bore into these materials to pupate. They are also a pest in the poultry industry (source (external link)).
- Dermestid beetles can eat cheese, feathers, fur, and leather. They may like cheese, but the latter are when other options are slim.
Here is a resource where you can learn more about Dermestid beetles and their care (external link), if you’re interested.
Feel free to leave a comment below if you have questions after reading this article! You can also ask us directly via our contact page.