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Caterpillars of Eastern Forests

Collecting Eggs

Often the simplest way to obtain caterpillar "livestock" is to capture mated females and hold them for eggs. Many species will readily deposit eggs if simply confined to a vial or bag for 1 or 2 days. Other species will not lay eggs unless cuttings from a larval food plant are placed into the container. Because some females require a substrate of a certain texture before they will release eggs, adding bark or toweling to the holding container can be helpful. Females can be maintained for longer periods by providing them with a honey or sugar water solution (add about 1.25 ounces of honey or sugar to 1 cup water). The solution can be offered in a saturated cotton ball—it is often helpful to uncoil the female's tongue and place its end in contact with the solution. Assuming the female is identified, this method has the advantage of yielding numerous individuals of a single, known entity. Well-preserved vouchers from such rearings have great scientific value.

Most species hatch 10 to 20 days after the eggs are laid. Others may overwinter in this stage—the first instars of the eastern tent caterpillar spend as many as 8 or 9 months entombed in their eggs. Eggs often darken just before hatching, and the caterpillar may be visible through the eggshell a day or 2 before hatch. Foliage and other plant materials left with eggs should be monitored, because molds may develop that can destroy the eggs. If there is doubt about an appropriate food, offer the young larvae a salad of plant species. The greater the uncertainty, the broader the selection you might offer. We suggest you start with black cherry and oak; birch, blueberry, and willow also are accepted by many species. If the species' identity is known, consult Covell (1984) or other references cited in the back of this guide for hosts occurring in your area. Younger leaves are preferred by many species—fully mature, hardened foliage can be lethal to many spring-feeding taxa. Conversely, mid-summer and late summer species often show a preference for older leaves.

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