Part of this contact is exploration and investigation into what caterpillars
and plants, butterflies and their predators, are all about. This
example of an investigative activity is included for students as well as
those of you who are curious and enraptured enough with butterflies to
go beyond the rest. In fact, there is plenty of room within the study
of Lepidoptera, including butterflies and their behaviors, life histories,
and interactions with other plants and animals, for pioneering research,
even in your own backyard. Not so much is known already that you
cannot make new discoveries of your own.
Dr. Minno assists students examining caterpillars and other insects shaken from a tree branch onto a white sheet.
Materials: Rearing containers, notebooks, pencils, rulers, butterfly eggs or caterpillars, host plant, and an emergence cage. Suitable rearing containers include plastic deli tubs, petri dishes, glass jars, or plastic shoe boxes. We prefer pint-sized deli tubs with a hole cut in the top of the lid, and a piece of screen glued over the hole. An inexpensive emergence cage can be made from a medium-sized cardboard box. Cut large panels from three of the sides and glue netting over the holes. Use a knife to make three cuts in the remaining side for a door. The uncut portion acts as a hinge. A drawer pull can be purchased from a hardware store, and installed as a door knob.
How To Do It: Look for butterfly eggs on a host plant such as Cassia, Fennel, or Passion-Flower. You may even be able to observe a female laying eggs in the garden. If eggs are not available, use small caterpillars. Cut some stems with fresh growth from the host plant to feed the caterpillars. Clean out the frass (droppings) and wash the rearing containers with detergent and warm water at least twice a week. Be careful not to disturb molting or pupating caterpillars. Replace wilted or excessively chewed host plant with fresh leaves. Transfer the chrysalids from the rearing containers to the emergence cage after the pupa has hardened. Record the date and time of egg hatch, larval molts, pupation, and adult emergence. Measure the length of the caterpillar’s body every few days. Retrieve the shed head capsules, and glue them to a card. Measure the size of the head capsules with a millimeter ruler. Make drawings or diagrams of the caterpillar’s color pattern at each stage.
Questions To Ponder: How long does each stage last? How does the caterpillar move? How is the pupa formed? How much larger does a caterpillar become at each molt? How much does head size change at each stage. Does the color of the caterpillar change at each stage or stay the same? Do bigger caterpillars make bigger butterflies? Are the biggest caterpillars males or females? What do the larvae and pupae look like to you? Crumpled leaves? Bird droppings? Scary snakes? Monster faces? What might they look like to potential predators such as birds or lizards? Which sex is the first to emerge, males or females?
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