Ohio State University Extension Fact Sheet

Entomology

1991 Kenny Road, Columbus, OH 43210-1000

Rearing Mealworms

HYG-2135-96

Mealworms are one of the best baits for bluegills, perch, trout, whitefish and many pan fish. Ice fishermen will catch many kinds of pan fish with mealworms when other baits fail. Bluegills prefer smaller baits after ponds and lakes are frozen. Yellow mealworms are known as "golden grubs" and often last on the hook longer than many other live baits.

Kinds of Mealworms

Yellow mealworm adult beetles are shiny black, whereas dark mealworm adults are dull black. Eggs are white, bean-shaped and about 1/20 inch long. Young larvae are white and darken with age. Mealworm larvae have a smooth, highly polished, shiny, elongate, hard, wormlike body about 1-1/4 inches long at maturity. Yellow mealworms are honey-yellow, whereas dark mealworms are yellow-brown. Pupae are first white before turning yellow.

Obtaining Mealworms

Mealworms can be obtained from pet shops where they are used to feed birds, reptiles and animals. Also, live bait stores sometimes sell mealworms. They often are found in granaries, feed stores and poultry houses.

Cages

Use a large, galvanized metal washtub, large bucket, crock or wooden box. A wooden box or flat about 8 to 10 inches deep, 2 feet long and 18 inches wide is a satisfactory cage. A suitable lid can be made by perforating small holes in a thin sheet of zinc cut to fit inside the box rim and resting the lid on a narrow wooden batten or strip all around. The cover is easily removed, allowing good ventilation. Some people use a fine- mesh screen cover.

Cage Preparation

Fill the box to within two inches of the top with wheat bran plus a small amount of dry brewer's yeast or graham flour and meat scraps. Alternating layers of chicken mash and burlap with about four layers of each may also be used. The chicken mash layer should be less than 1/4 inch thick. Spray the surface lightly with water and keep it damp with daily sprinkling - do not soak.

Biology

The yellow mealworm is the kind most used for fish bait. A culture can be started by introducing from 500 to 1,000 larvae or beetles in a wooden box 8 to 10 inches deep, 2 feet long and 18 inches wide. Each female can lay some 275 eggs, with larvae completing their growth in six months or less at 80 degrees F. Larvae molt 9 to 20 times before reaching adulthood. Mealworms are easy to raise and multiply quite rapidly with a constant temperature of 80 degrees F. Temperatures can vary from 65 to 100 degrees F.

Feeding

Mealworms are cheap and easy to raise. Feed may consist of wheat or corn bran into which is mixed about 1/4 part of poultry laying mash. Since mealworms prefer moist foodstuffs, their diet should be varied by adding slices of potatoes, carrots, lettuce or other vegetables from time to time. Place these vegetables on a thin board or metal on top of the bran. This tray can be removed at intervals and cleaned. Keep the bran from becoming too moist or molds and mites can develop, ruining the culture. Apply fresh bran as needed; this alone is a staple diet.

Other Factors

If too little moisture is in the bait, growth will be slowed and size reduced. If too much moisture is in the bait, it can become moldy and poison the larvae. Maintain suitable moisture by placing pieces of cabbage, carrots, lettuce or potatoes near the top of the bait. Use one type vegetable at a time to provide adequate moisture for both adults and larvae. When larvae are nearly mature, place corrugated paper, rough burlap or crumpled paper toweling in the cage. Let adults emerge before disturbing. Avoid too many adults in the cage because they can eat eggs and reduce the population. Harvest the larval fish bait just before pupation begins or as needed. In a short time you will have all the mealworms you can use. Size is largely a matter of feed and temperature. If kept at a temperature of about 38°F, mealworms can be stored almost indefinitely. Care must be taken not to freeze them. Observation is the secret of raising mealworms.