Visit -- www.Butterfliesetc.com-- for Your Living Butterfly Needs

Lifecycles

Lifecycle Facts

Raising Butterflies

Free Downloads

Butterfly Identification

Butterfly Parasitoids

Butterfly Enemies

Butterfly Disease

Butterfly Plants

Plant Pests

Butterfly Gardening

FAQ

Odds and Ends

Ask Edith

Butterfly Plant Recipes

Why Are Some Butterfly Chrysalises or Adults Larger than Others?
Chrysalis (or pupa) size within the same species will vary for several reasons.

Size of the adult butterfly is determined by size of the chrysalis.

One reason is simply whether the butterfly is a male or female. In some species, like the Monarch, male butterflies are larger. In other species, like the white Peacock, the female butterfly is larger than the male.

Another factor is its diet as a caterpillar (larva). The more a caterpillar eats, the larger it will grow.
Several photos below illustrate the difference in size that occurs when one caterpillar has less food to eat.
If the preferred host plant is not available, the caterpillar will eat a host plant which it doesn't usually eat. If it is not the preferred plant, it will not eat as much. Some host plants have large soft leaves and are easily eaten. Other plants have small and/or tough leaves which are harder to eat or the caterpillar may find it harder to find enough leaves to eat. If the caterpillar has to travel to look for another host plant after it has eaten the first plant, energy from its meal will be used to travel instead of being used to grow larger.

I use the Common Buckeye (Junonia coenia) to illustrate this in photos below. Cudweed has very few leaves and almost all leaves are at the base of the plant. It grows only in the spring. False Foxglove grows only in the fall and also has small leaves but does have more leaves per plant. It is not unusual, in our area, to find a dozen or more caterpillars on one plant. Not only do they strip the plant of leaves, they also chew on the stems, completely eating the outer layer in some cases.

Disease can cause a caterpillar to eat less.
Many butterfly and moth (lepidoptera) diseases cause a loss of appetite.

An adult butterfly or moth never grows. Its wings will not increase in size
after it emerges and pumps fluid into its wings and the wings dry.
Two sizes of Monarch
Danaus plexippus chrysalises.
Two sizes of White Peacock
Anartia jatrophae, chrysalises.
Two sizes of Common Buckeye
(Junonia coenia) chrysalises.
Buckeye eating Blue Toadflax.
Note the small size of the leaves.
Buckeye eating Cudweed, not a preferred host plant.
Buckeye eating Cudweed,
closeup of same photo.