Raising Mealworms

by Elizabeth Ann Shenk | Apr 5, 2022 | 0 comments

Eastern Bluebird eating mealworm in pink flowering tree
Eastern Bluebird eating mealworm. Photo © Dreamstime.com.

Thank you to the Amstutz family who asked about raising mealworms for bluebirds (February issue). I can hear and see your bluebirds’ happy warbling and excited fluttering when they find their feast.

When we began raising mealworms, we bought plastic shoe boxes at a department store for containers for the culture. You may use larger boxes. Some people use plastic buckets.

To feed the worms, we put three inches of oatmeal in the boxes. Some people use part cornmeal, or one part chick starter to one part wheat bran.

Cut an apple in half, and, with the round sides down, press the halves into the meal until the cut side is flush with the meal. This provides moisture for the mealworms to keep them growing faster. To avoid spoilage of the feed, caused by moisture in the apples, DO NOT peel the apples. When the apples are mostly eaten, or spoiled, replace them. Instead of apples, you may place a fresh banana peel, every day, moist side up, on top of the feed.

To each shoe box we added fifteen to twenty mealworms. For a larger container, add more worms. We found our mealworms in a calf barn among discarded feed bags. Mealworms can also be purchased at stores selling fishing supplies.

We laid four layers of paper, cut from brown grocery bags, over the feed, apples, and worms. They like hiding between layers of paper. They eat some of the paper also.

For ventilation, drill many tiny holes in the container lids, or cut the center out of the lids and attach window screen material. Or drape netting over the top of the container; then press the cut-out lid down over the netting. Provide enough ventilation to avoid molds from condensation.

Mealworms are larvae of a species of darkling beetle. Each worm will turn into a pupa, then into a beetle. The female beetles will lay eggs, then die. This completes their life cycle.

Eventually you will see hundreds of itty, bitty mealworms. They are so small that at first they just look like a stirring in the feed. Wait for them to grow.

This cycle takes about three months. If possible, keep your culture at room temperature or warmer. If the environment is cooler, they grow more slowly. In winter, if they are in an unheated place, they stay dormant.

If your container is transparent, you will see a layer of excrement at the bottom by the time the feed is mostly consumed. It looks like gray sand. It is odorless. You may add more meal on top, as needed, until the container is too full, or you may start a new culture now. We take worms from the earlier culture to begin a new one.

You want to feed your bluebirds this summer. Will this cycle take too long? While your culture is in process, you may find mealworms in a barn as we did, or you may buy them.

For feeding the birds, we cut the bottom from a gallon plastic jug to make a bowl two inches high. Slick, straight-up sides prevent the worms from crawling out. To keep the bowl from blowing away in wind, we put a stone in it. We put some mealworms in the bowl and set it on the ground under the bluebird house. It didn’t take them long to find it. Daily we moved it a little closer to our house. After a few days, we were feeding the bluebirds from our deck right outside our family room window. Fun!

Downy Woodpeckers, Carolina Wrens, and other birds that eat insects, come for mealworms also. Whistle or ring a bell every time you put out mealworms. Bluebirds warble back. When he’s around, Carolina Wren loudly chants, “Chirpity!” every time I whistle. I believe he thinks I sound more like a wren than a bluebird.

Sometimes birds carry mealworms to nestlings and fledglings. Sometimes they bring fledglings to the deck and teach them to eat from the bowl. Sometimes in winter we feed six or eight bluebirds.

We don’t manage our “hatchery” well enough to keep a non-stop supply of mealworms. To have other food for bluebirds, to keep them coming, we make a mixture of four parts oatmeal to one part fat. For fat, we use tallow, lard, chicken fat, or peanut butter. We serve one-fourth to one cup of these crumbs a day, depending on how many birds are coming.

We’ve also harvested dogwood berries in autumn, put them in bags in the freezer, and served them throughout winter. Bluebirds eat other berries too: blackberries, raspberries, pokeberries, bayberries, mulberries, elderberries, serviceberries, and berries from Virginia creeper, juniper, burning bush, and deciduous hollies. Wild grapes and sumac are some of their favorites.

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