Growing Mealworms

Mealworm Substrate, Food and Water

The mealworms substrate is also their food. Providing a fine substrate will assist in the activity of the colony since eating will be less difficult than when providing whole rolled oats or similar. This is easily achieved by putting the mix to be fed in the blender first.

Mealworm food and substrate ground up

Mealworm food and substrate ground up and ready for mixing and bringing in the new colony members.

The substrate itself will ideally be a mixture of grain products and some brewers yeast. The substrate in the image is being prepared for a colony in its 11th generation which are about to be transferred to a  fresh substrate. The mix is wheat, rolled oats, pollard, a small amount of low fat dog biscuits along with a small portion of brewers yeast. All ingredients have been frozen overnight to eradicate any pests it may be harboring. Once ground it is added to the container ready for mixing together.

Mealworm food and substrate not ground

Mealworm substrate not ground up. Slows down consumption and ultimately the productivity of the colony.

Unless you are entering into a commercial mealworm business then the mix is not precise and can be adjusted as required. You could of course simply provide rolled oats, but it is not so easily eaten and that has the potential to slow down the rate at which the colony will grow and reproduce.

Raising mealworm colony infested

Mealworm colony infested with moths

Before using the substrate put all the ingredients in the freezer. The chances of moth eggs or larvae are in the products to be used, even if they are for human consumption, and freezing for a day will kill the unwanted extras.

Moisture is one of the biggest threats to a colony and needs to be managed. The surface can appear fine whilst a moist gluggy mess can start to emerge at the base. One means to monitor and assist in controlling it is to gently mix up the substrate from the bottom to the top every few days by placing your hand into the substrate down to the bottom of the container and scooping it up to the top.

Fresh vegetables are provided for moisture. Although apples and potato are often seen provided whole, this will only contribute to moistening the substrate and potentially bacteria levels with it. There is little more work involved by offering fresh vegetable daily or even every 2nd day, but it provides a much safer alternative than leaving it to rot and far less work than having to move the colony to a new substrate if the substrate becomes destroyed. Leaf vegetables and carrots provide all the moisture needed and in my experience are eaten far more readily than potatoes or apples.

Keeping all Stages of Mealworms Together – Hazards and Solutions (Breeding Mealworm Colonies)

Overcrowded conditions when growing mealworms

Overcrowding increases the number of beetles hatching damaged

Keeping all stages of mealworms together is far more convenient than going through the process of keeping them separated. However the hazards are that the pupae may become injured resulting in beetles with damaged exoskeletons (such as in the photo) or even death in the pupae stage. Since keeping all stages together is the most convenient method of managing colonies (excluding commercial production), the colony can be managed by other means to reduce the damage of future stock.

Ensure the colony is not overcrowded. Provide adequate nutrition, oats is not enough. Provide vegetation for fluids, this is better done daily than leaving moist foods for the week in the substrate which may result in growth of bacteria and add excess moisture to rot and spoil the substrate. Although they can survive much longer than a few days without fluids, fluids increases the activity and health of the colony. Provide plenty of rolls (ie toilet or paper towel rolls cut to the size of toilet rolls) for the mealworms to climb into when they are ready to pupate. The rolls should very slightly upright, but not fully. Fully upright will result in a mass of mealworms pupating on top of each other making it very difficult, if not impossible, for the new beetles to work they way out of the mass, especially in the fragile state before the exoskeleton has hardened. Placing the rolls on an angle will fit more but the weight on top of the ones on the bottom is limited to the width of the roll. If they are laid flat then the beetles have a tendency to wander in and out of the rolls more frequently than if sloped. On top of that, the worms simply seem to prefer to climb into secluded spots for pupating.

These methods will not prevent damage altogether, some pupae are still likely to be damaged. Should any be damaged, just feed them to the bearded dragon rather than leaving them in the colony.