• Butler SWCD

Milkweed Tussock Moth

Milkweed's not just for Monarchs


Do you have hordes of hairy black, orange, and white caterpillars munching on your milkweed? If so, congratulations on meeting the milkweed tussock moth, an Ohio native.


The caterpillars go through a number of instars, or growth stages, before reaching their largest larvae stage. The first instar for the larvae are often difficult to detect. They are initially pale yellow and bristly with black heads. These young larvae travel in a little fuzzy herd on the underside of leaves. The little larvae strip the tissue off the leaves, but avoid the veins because there is a great deal of latex-like white sap that could glue them in place.

As the caterpillars mature, they become covered in thick hairs with many black, orange and white tufts. Sometimes they are called milkweed tiger moths due to this coloration. The large herd of caterpillars will separate into pairs or even individual caterpillars, continuing on their journey of munching milkweed. At this point, if there are other common milkweed in the vicinity, some of the brightly colored larvae will migrate there. They build up antifreeze in their blood in the early fall, to keep from freezing over the winter as they pupate. They pupate in small, gray felted cocoons until the next spring. Emerging in the Spring, the adults, like many moths are not as colorful, being mainly a soft grayish brown.

The milky sap and cells within the milkweed leaves contain harsh chemicals, including toxic cardiac glycosides. Many insects that eat milkweeds have evolved mechanisms to deal with these toxins, and store the noxious compounds in their bodies. Caterpillars of both the monarch butterfly and milkweed tussock moth obtain cardiac glycosides and retain them as they develop.


Some nature lovers want to protect the milkweed just for monarchs. Although, we can't deny that milkweed tussock moth caterpillars are serious milkweed munching competitors to monarchs. However, the tussock moths are also native insects; they should enjoy the same rights to milkweeds as the colorful monarchs. Species diversity is an essential part of a healthy ecosystem.


On a final note, be wary handling the colorful caterpillars, their hair can be an irritant.


If you would like to meet some of these fuzzy creatures...

Join Butler SWCD on Tues, Aug 25 at 6 pm. We are hosting a volunteer event to remove invasive plants from a pollinator project in West Chester. While we are there, we will be photographing as many species of pollinator as we can. You can help by bringing your gardening gear, or your camera. Or, just join us to have a look at the many species of plants and animals at this project site.

Park in the Hopewell school parking lot on the corner of Barret and Cox Rds, in West Chester.

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