Prairie Ridge Ecostation

American Dagger Moth Caterpillar

Prairie Ridge is home to many species of butterflies and moths and some of those species have spectacular caterpillars.  One of the most interesting is the American Dagger Moth caterpillar (Acronicta americana).

American Dagger Moth Caterpillar

American Dagger Moth caterpillars are large caterpillars that are clothed in long white or lemon yellow hairs.  Their distinctive characteristic is the pattern of black tufts: two pairs of diverging tufts along the middle of the caterpillar and one thick black tuft at the end.  The caterpillars are typically yellow in the early and middle stages of their development, but turn pale yellow or white as they near pupation and begin to build a cocoon.

American Dagger Moth caterpillars are a forest moth species that feeds on a wide variety of trees.  These include alders, maples, oaks, walnuts, willows, and poplars.  In their early stages, the caterpillars will rest on the underside of the leaves and chew the soft tissue between the veins.  As they age, they are able to eat more of the leaves and can occasionally be considered a pest.

The caterpillars of the American Dagger Moth are commonly observed well into the fall, until the end of October or early November.  At the end of the season, they will pupate and overwinter inside their cocoons before emerging as large, brown moths the following summer.

These caterpillars have been known to cause a mild allergic reaction in some people, a rash across the area that came into contact with the hairs.  It is unlikely you will get a rash if you allow the caterpillar to crawl across your hand or lightly brush up against the hairs accidentally.  However, if you have sensitive skin, it is probably best to leave them alone entirely.

If you want to see an American Dagger Moth caterpillar, Prairie Ridge is a great place to visit!  They've been recently spotted along the Forest Trail, climbing on the tree trunks near the creek.  Be on the lookout for big, fluffy yellow caterpillars as you walk the trail!

Find out more about the natural happenings at Prairie Ridge at our What Time is it in Nature Archive.