masthead graphic
Illinois Butterflys & Moths
Photo Gallery
ISM System :Butterfly and Moth Introduction

Introduction to Butterflies and Moths

This introduction is an excerpt from the Illinois Butterflies and Moths poster information published by the Illinois Department of Natural Resources.

Butterflies and moths (Lepidoptera), like other insects, have three main body parts — head, thorax, and abdomen. They also have three pairs of legs and a pair of antennae. Most have two pairs of wings that are covered with tiny scales. The arrangement of the scales is responsible for the diverse patterns on the wings of the various species. A few species are wingless, including, in Illinois, the female bagworm moth (Thyridopteryx ephemaeriformis) and the female white-marked gypsy moth (Orgyia leucostigma).

Anatomy of the Adult
photograph of cecropia mothThe mouth parts of adults are modified into a tube-like proboscis for taking in liquids such as nector or sap. The proboscis is coiled at the front of the head when not in use. Some species, such as the common Illinois moths cecropia (Hyalophora cecropia, pictured here) and luna (Actias luna), do not feed as adults.

Anatomy of the Larva
The cylindrical larva (caterpillar) is soft-bodied. It has a hardened head with chewing mouthparts (mandibles), well-developed maxillary palpi (finger-like structures) for food handling, and spinnerets (tubes from the silk glands) for releasing silk.
The thorax has one pair of legs on each of its three segments. Spiracles for breathing are found on the thorax (one pair) and the abdomen (one pair on each segment). Abdominal segments three through ten have prolegs (fleshy legs without joints). The prolegs often have little hooks (crochets) that let the caterpillar cling to leaves and stems of plants. The body may also have spines, hairs, or bumps. Colors range from camouflage to bright warning. Some species, such as swallowtail larvae, give off a disagreeable odor.

Is It a Butterfly or a Moth?
A key characteristic in telling whether a given individual is a butterfly or a moth is its antennae. Butterflies usually have threadlike, knob-tipped antennae. Moth antennae have many shapes, including a feather shape (such as in the image above), and never have knobbed tips. Generally, moths' bodies are fatter and more feathered that bodies of butterflies.

Life Cycle
Butterflies and moths undergo a complete metamorphosis (change in form) of four stages:

photo of monarch egg and larvaEgg: Eggs are laid singly or in clusters on or near a host plant.

Larva: Larvae of some species feed on one plant, while many other larvae feed on many plants. The larvae grow and molt (shed their exoskeleton).

Adult monarch emerging from cocoonPupa: The larva of many species of moths and some species of butterflies spin a cocoon in which to pupate (transform into the adult stage), usually on or near their host plant. Other species pupate in a sheltered area such as leaf litter or in the soil.

Image: Adult emerging from a chrysalis.

Adult: The pupal skin splits apart, and the newly formed, soft adult emerges. Most adults live only about two weeks, during which they mate and lay eggs. Some species overwinter in one of their stages, and adult monarchs (Danaus plexippus) and painted lady (Cynthia cardui) migrate to Mexico in the fall.

Related Activities:
Symmetry in Art (html) (pdf)
Butterfly Poster
(html) (pdf)

Copyright © 2012 Illinois State Museum Site Map | ISM Privacy Information | Kids Privacy | Web Accessibility | Webmaster| Illinois DNR