Care and Breeding of Mealworms

Supplies

1) Dry Food (examples in article)
2) Wet Food (examples in article)
3) Mealworms
4) 3 containers (at least one with a lid, size depends on how many mealworms you start with)
5) Paper towel tubes or paper egg cartons

Mealworms are the larvae of a species of darkling beetle (Tenebrio molitor). They have been a popular feeder insect for years. Mealworms are extremely easy (and cheap) to care for. The mealworm life cycle takes 3-6 months so plan ahead. Like most insects they go through complete metamorphosis (egg, larvae, pupa, adult beetle). If you use them often you should consider raising your own. It is an interesting and fulfilling experience for a herper.

Start with a smooth sided container with or without a lid for the larvae. Cover the bottom with about 1.5 in of oatmeal. This will serve as the bedding and dry food. To make it more nutritious you can add a little brewers yeast, wheat germ, whole wheat flower, fish flakes, or ground up dog food. To this add your mealworms (no less than 100 to start a colony, preferably 500 or more). They will need a water source. This will be provided by fruit and vegetable slices laid on top of the bedding. You can use potatoes, carrots (best), banana peel, cabbage, yam, and apple (worst).

Daily maintenance will include removing moldy wet food, adding fresh wet food, removing dead insects, and checking to see if any larvae have turned to pupa (they will look pale slightly curled and won't move unless touched).

Any pupa you see should immediately be removed and moved into a second container with a tiny bit of bedding (no wet food). Pupa must be separated from adults and larvae so they don't get chewed on. When the pupa become dark in color it means they are about to turn to beetles. Any beetles that hatch should immediately be moved to a third container that is setup like the larvae container. The beetle container should have a lid so they don't escape and you may also add paper towel tubes or egg cartons for hiding spaces. The beetles will mate and lay eggs in the substrate, and after a couple of weeks it should be full of eggs and tiny larvae. At this stage I have heard of people putting the substrate over a wire screen sat over another container. The idea is the tiny mealworms will burrow to the bottom of the substrate and fall through the holes in the screen to separate them from the adults. I just pick the beetles out and let their container become the new larvae container. The old larvae container can be cleaned out and used for the next batch of beetles.

Stage Durations

Egg- 4-19 days
Larvae- About 10 weeks
Pupa- 6-24 days
Adult- 8-12 weeks

The length of each stage depends on temperature and nutrition. Higher temperature will make them grow fast. More nutritious food will make them grow faster.