Do not get too close to or touch this seemingly harmless caterpillar. It has the ability to spray formic acid, the same substance in ants, which can cause blisters on contact, and strong irritation to skin and eyes. An assortment of beetles, wasps, and parasites still attack this caterpillar despite its chemical defense, and this helps manage population sizes. These natural predators are varied and common so it is not considered necessary to treat areas where the caterpillar is found. Occasional severe defoliation can occur, but only one generation is produced each year and outbreaks generally last only one or two years. The loss of leaf cover and brown droppings left by the caterpillars can diminish the aesthetics of the tree.
The variable part of the name stems from this caterpillar's varied patterns. It may be leafy-green with a yellow or white line running down each side of its 'back'. Just behind the head, these two lines are close, and the narrow space between them may or may not be red. Another form is green on the side with a wide brown band on top. Brown may blotches break through the band. A caterpillar may have a bit of each of these variations and be mostly green with brown spots on top every few segments. The head helps unite the species as the various patterns all seem to have a striking black and white stripe on each side.
The moth is active from spring through autumn, and caterpillars are active from late summer through the end of fall. Larvae take cover in silk cocoons during winter and pupate the next spring.
The map above showcases (in blue) the states and territories of North America where the Variable Oakleaf Caterpillar may be found (but is not limited to). This sort of data can be useful in seeing concentrations of a particular species over the continent as well as revealing possible migratory patterns over a species' given lifespan. Some species are naturally confined by environment, weather, mating habits, food resources and the like while others see widespread expansion across most, or all, of North America.*NOTE: States/Territories shown above are a general indicator of areas inhabited by the Variable Oakleaf Caterpillar. Insects generally go where they please, typically driven by diet, environmental changes, and / or mating habits.