Mealworms & Other Live Food
About MealwormsMealworms are particularly useful as a rearing food for young, insectivorous finches. If you are breeding finches who require live food to rear their young, mealworms are great because they are very easy to acquire and/or raise at home. The worms are the larval form of the beetle Tenebrio molitor10 whose life cycle is divided into 4 stages: egg, larvae, pupae, and adult. The young larvae are the best to feed, especially if they have just recently shed their chitin skin, leaving them white in color, soft in body, and easy to eat. Boiling and/or chopping the mealworms into pieces are other ways to make the mealworms easier for a bird to consume. Mealworms may be advertised in different size classes, including mini, small, and giant; I prefer the small type. They can be obtained from some pet stores (especially those which specialize in reptiles), or at tackle and bait stores. They are usually sold in small plastic containers that contain a little bran and about 50-100 worms. The containers are kept refrigerated to slow the mealworms' life cycle down into what is called "suspended animation." These refrigerated worms will not breed. When mealworms make up a significant part of the diet, additional calcium must be added to bring the diet to the proper 2:1 calcium:phosphorus ratio.7
Raising MealwormsIf you have a very large collection of mealworm-eating finches, you way wish to raise the worms yourself. A 10 gallon fish tank or a medium sized plastic critter keeper (available through pet stores) will serve as the breeding container. A lid over the tank will prevent any escapes. Fill the bottom of the container with 1-2 inches of bran mixed with ground-up Science Diet dry dog food, eggshell, Cheerios cereal, and hulled sunflower seed kernels. Insects for feeding insectivorous birds should be raised on these high protein and calcium gut-loading supplements, because if they are fed on vegetable matter or bran alone, their protein and calcium content may be too low.7 Keep the container at room temperature indoors so that it cannot become contaminated. Purchase about 200 mealworms initially so that enough will survive to reproduce, and you'll have some extra worms to begin feeding your birds. Introduce the worms into the tank; once they begin to warm up, they will start moving around a lot more, and their life cycle will resume to its normal pace. The worms will need a moisture source, which can be obtained by slicing an apple and placing the slices in the container with the worms. Remove and replace any slices that become dried out or molded with fresh slices. Other possible moisture sources include celery, other chopped fruits, and lettuce.
Larvae take approximately 10 weeks from hatching to develop into pupae, shedding their skin about once a week. For the first several minutes after they shed their skin, the larvae are white, and gradually become darker until they return to their normal golden-brown color. (The best time to feed mealworms to your finches is while they are soft and white.) When you notice that the worms are beginning to pupate, place a piece of crumpled and re-flattened paper over the substrate, and put a few moisture sources on top of it. This will allow for the escape of mutating worms so that once they are defenseless pupae, the other worms cannot devour them. Usually within about a week, the pupae will hatch into beetles. A few weeks after that, the beetles are sexually mature and begin mating. Eggs are laid and hatch within two weeks. The eggs are small, and white; each female beetle can lay up to about 275 eggs. The eggs are also sticky, and often cannot be seen because they become coated in the surrounding substrate's "dust." The newly hatched worms are often too small to be seen. Once the worms are large enough to be easily seen and picked out from the bran, begin collecting them for your finches. A good size would be about a ½" long, preferably while the worms are still white (but this is not necessary). You may wish to boil and/or chop up the worms to make them easier to eat as well as to prevent their escape. Some finches may prefer to eat the pupae instead of the larvae.