Mealworm Colony
& Why I Wanted To Be Self-Sustaining
I started my mealworm colony about a week and a half after I bought my geckos. After the first few days of owning the geckos and seeing just how much they eat, I decided I didn't want to be spending $20 to $40 a month just on food for these guys. It racks up pretty fast. Considering that as babies and juveniles they eat anywhere between 5-15 mealworms a day. Multiply that by 3 geckos and you've got anywhere between 105 to 315 worms a week. A 500 count of giant mealworms costs $10 locally, so you can do the math, but it makes more sense to start up a mealworm colony and be self-sustaining. It's more money up front, but saves in the long run. And also, if you're like me and love birds, if you ever have any extra in your colony, while still maintaining your supply, and you've already put some in the refrigerator for your reptiles to munch on for awhile, then feed the leftover worms to the birds outside. Remember though, don't release them in the ground, they are not native to your area unless you live in the Mediterranean region, and can become pests that will eat on grains on local farms. So use a big enough bowl (about 2-3 inches deep) that the worms and the darkling beetles that have already mated can't crawl out of.
Mealworms to Darkling Beetles
The life cycle of the Darkling Beetle is quite interesting. This website goes into more detail about the life cycle, but to cut it short: They start out as eggs, and in about 1-4 weeks they hatch and become mealworms. The worm (pictured above top left), also known as the larva stage, go through several molts that can take about a month to two months to complete. It all depends on temperature. My temperature stays at the perfect 75-78 degree range which speeds up the process. Then they turn into the pupa (pictured middle left) which looks like some kind of creature from the movie Aliens. They don't do anything in this stage, they just wiggle if you pick them up. This stage lasts one to three weeks. Because of my temperature it lasted maybe a week to a week and a half. Then they transform into beetles (bottom left and right picture). The beetles will come out white and tan, then within 24-48 hours they will turn dark black. That is when you know that they are sexually mature. Once they turn black they will pair off and start to mate. I've had my colony going for five weeks now and my darkling beetles are starting to mate. Once they've mated the females will lay eggs and we start the whole process over again. Also, once the darkling beetles mate, they will only last maybe 3 months, so you can use them at that time for feeding birds outside. Just make sure they lay the eggs. Each female can lay around 500 eggs.
How To Start Your Mealworm Colony
Containers:
You can use just about any container, but I prefer these critter keeper containers I got from Petco for about $14 each. They already have the perforated lid so you don't have to DIY and drill holes and attach screens or cheesecloth to keep other critters from getting in. I have 2 of the larger size, as well as some smaller betta containers to keep the pupa in. Because the pupa does not eat in that stage, you don't have to line it with oats, but you do need to make sure that there are a few pieces of oats and veggies in there for when the beetles hatch, as well as a few paper towels just in case the beetles can't flip over, it'll help them crawl around.
You want at least 3 containers, one for each stage of the transition. I actually have 4 because once the darkling beetles lay the eggs you need to pull the darkling beetles out so they don't eat the eggs. You also don't want the beetles or mealworms in with the pupa, because they will eat the pupa. It would also help to have an extra container on hand for sifting out the dead worms and frass (mealworm poo) just in case a mealworm or two gets through your strainer during cleaning.
Substrate:
Once you have your containers you want to line them with some type of grain for your substrate. I prefer oatmeal, aka, oats. These you can get from your local grocery store. I use the store brand Old Fashioned Rolled Oats. Most important... NO FLAVOR ADDED. No sugar. NOTHING! Just plain old oats. I've read others use wheat bran and even crushed up dog food. The reason I use the oatmeal is because it's healthier. But also because when you sift out the frass, which you will have to do bi-weekly to monthly, is that you don't want to waste your oats. There is an excellent video here on sifting the frass. Frass can also be self-sustaining as well. If you have a garden or plants/flowers it makes an excellent fertilzer! I'm giving my frass to a family member who has a garden and compost set up. It'll go great in the compost bin. You'll want to make sure you do about an inch or two of oats for the substrate to give the worms and beetles plenty of room to hide. They don't like light much.
Food & Water:
They will munch on the oats for food, but they do need a water source. You can get this by using carrots preferably, but potatoes, celery, and apples will work as well. You don't want to go too sweet, so I wouldn't use the apples too much. Remember, you want your geckos (or other reptiles and animals) to be happy and healthy, so feed your mealworms very good to make sure your critters get the proper nutrition they need. If you go too sweet, then it can affect your geckos. I also have a self-sustaining option for this as well. I juice vegetables and fruit for myself. If you know anything about juicing, you know there is a lot of pulp left over. Some of this pulp I feed to my dog because it's healthy for him, and then I also put some of the pulp in each container in a lid so that the worms and beetles can crawl in and munch. I would only do carrots, celery, and apples for the juicing portion, no other fruits. Always research what is best for your particular animal. We don't want diabetic lizards now do we? Also... In the picture above with the carrots laying on top of the oats, is something I started out doing until I read that it can cause a mold problem in the oats, and you want your oats to be mold free, obviously. So now I have a little plastic lid from an old rice container that I use to put all the veggies and fruit on. You just want it deep enough so that the worms can get in and out of it with ease. Trust me, they'll find the veggies!
In Conclusion:
I know it seems like a lot of information, but honestly, a mealworm colony is one of the easiest things you can do. It's self-sufficient, you only have to really do work on it every few days (just to make sure you pull out the pupa and beetles as they turn), and to make sure they have food and water. I find myself working on it every day or two, but mostly because I'm fascinated by it. I'm a geek like that. I love learning, I love research and I love nature. I think doing this woud be a great way for children to learn to be self-sustaining and help them to learn how to properly take care of their pets.
Sidenote:
When I first started my colony I made the mistake of buying Giant Mealworms. I later read online that giant mealworms are genetically modified to grow larger, and once they become darkling beetles, are actually sterile. I don't know if this is true or not. I have tried to contact the company I bought the worms from and they gave me a base answer of the larger an animal/insect is the more likely it is to be sterile. I will know in a couple of weeks if that is true. So when you go to start your colony, I would say it is probably safer to use small mealworms. It might take a little longer but at least you won't be wasting money like I did. I have since added a mixture of large and small mealworms to the mix just to be on the safe side.