Common Buckeye – Junonia coenia

Common Buckeye butterflies are found in the southern half of the US and the eastern side of the northern half of the United States.

There are two similar species.  TheMangrove Buckeye Junonia genoveva  is found in the southwestern United States and in the southern tip of Florida.  Tropical Buckeye butterflies Junonia evarete  are found in the southern tip of Florida and the southern tip of Texas.

Female Buckeye butterflies are larger than males. They drink nectar from flowers with a short throat. Their proboscis isn’t long enough to reach the bottom of long tunnel shaped flowers.

Buckeye butterflies lay eggs singly on their host plants. Unlike some butterfly species, Buckeye butterflies lay eggs on a wide variety of host plants. Some of their host plants are Blue Toadflax, Plantain (Plantago species), False Foxglove, Mexican Petunia (Ruellia species), Firecracker, and Cudweed. Caterpillars are dark in color and eat alone. A caterpillar is often overlooked until one sees the leaf damage from a hungry caterpillar.

Eggs are green and laid singly on host plants. The eggs blend well into the plant. Eggs are tiny. A hatchling Buckeye caterpillar is smaller than many other species simply because it must fit inside the egg before it hatches.

In some areas of the US, Blue Toadflax is an annual that grows early in the spring. It may take several plants to feed one caterpillar to pupation.

False Foxglove, another annual, sprouts in the spring and blooms in the fall. In north Florida, as Buckeye butterflies migrate south, they lay eggs all over flowering False Foxglove. Although caterpillars can be found on these plants earlier in the year, it is during the migration that many of the plants are stripped of all leaves and blooms by hungry caterpillars. False Foxglove flowers may be lavender/purple, white, or yellow.

Caterpillars eat several species of Plantain. Occasionally caterpillars have eaten Philippine Violet and, in captivity, eaten all the leaves on and pupated on one type of Butterfly Bush, Buddleia sp. They have been seen eating Lantana on occasion. Each of these unusual host plants were actually eaten. The caterpillars were not simply resting on the plants.

A caterpillars outer exoskeleton is often called ‘skin’ but it is actually a cuticle. Skin is a living organ. A cuticle is more like a pillow cover. The cuticle never grows. When the caterpillar grows too large for its cuticle, it will molt. Underneath the old cuticle is a larger baggy cuticle. Buckeye caterpillars molt four times before they hang in a J to pupate.

Gardeners often worry when their caterpillars disappear off the host plant. Predators are the reason most caterpillars disappear. But if the caterpillar was ready to pupate, it often leaves the plant to do so. Caterpillars may wander 100′ or more before pupating.

Once it has decided upon the spot it will pupate, the caterpillar begins to make a mat of silk.  In the middle of the mat makes a tight silk button. The silk comes from spinnerets underneath its head. It attaches its anal prolegs to the button and, over the course of the next hour or so, drops into a J shape. After a day, it again sheds its cuticle and the chrysalis (pupa) is what remains. A chrysalis is literally a caterpillar that has skinned itself.

Chrysalises vary in color from light to dark brown, depending upon where they pupate. If they pupate in bright light, the chrysalis will be extremely light. If they pupate in an extremely dark area, they will be extremely dark.

One to two weeks after the caterpillar becomes a chrysalis, depending upon the temperature, the adult butterfly will emerge. Their metabolism slows during cooler temperatures and delays development. In the middle of the summer, the adults emerge in about seven days. In late fall with temperatures dropping to the 40s at night, they take two weeks and sometimes longer to emerge as adults.

A day after emerging, the butterflies will begin to drink flower nectar. Buckeye butterflies also drink from fruit.

This Buckeye is drinking ‘fruit’ that is poisonous to many mammals. It is drinking from the pulp (fruit) around a Lantana seed.

Male butterflies drink from ‘food’ sources that female butterflies ignore. This Buckeye is drinking from a rotting dead deer. The deer was killed by a vehicle as it crossed the road with incredibly bad timing. A few days later, the deer was rotting and had a very unpleasant odor. Male butterflies were drawn to the deer and feasted for hours. Although I enjoyed taking these photos, my nose was not happy with me.

In the Spring and Summer, the underside of a Buckeye butterfly’s wings are lighter in color. This provides a better camouflage than darker wings as plants are growing and lighter colors are present in nature.

In the Fall and Winter, plants are dying or dead and nature turns brown. In those seasons, the underside of a Buckeye butterfly’s wings are darker in color. Again, this provides better camouflage.

When a female Buckeye butterfly wishes to reject the advances of a male butterfly, she lifts her abdomen into the air. He cannot pair with her as long as she holds this position. To pair, the male swings his abdomen under her wings to reach her abdomen. Many people mistakenly assume that the lifted abdomen is an invitation to male butterflies but it is quite the contrary!

At Shady Oak Butterfly Farm, we carefully selected adult butterflies to create a line of blue, green, and purple Buckeye butterflies. With the same iridescent blue as a male Pipevine Swallowtail, these Buckeyes are striking in appearance.