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The American dagger moth is abundant in most US states that lie east of the Rocky Mountains. This moth species is active in between the spring and fall seasons within Massachusetts. While dagger moths may not be considered a pest, their larvae (caterpillars) can pose a threat to people living in suburban neighborhoods. Dagger moths and their caterpillars prefer to dwell in areas containing deciduous trees, which are often found in parks, forests and backyards. Dagger moth caterpillars are hard not to notice when they maintain a presence within residential yards, as these two inch long caterpillars possess bright yellow hairs that protrude like quills from their body. Black hairs can be seen protruding from this caterpillar’s rear area. Despite this caterpillar’s fascinating appearance, these black hairs are actually urticating hairs that become detached into skin where they release a venom into the bloodstream. Although dagger moth caterpillar stings are painful, they are largely harmless to adults, but children, the elderly, and those with venom allergies can become hospitalized as a result of sustaining a dagger moth caterpillar sting.

Dagger moth caterpillars are common in backyards due to their habit of feeding on trees that are common in residential areas of Massachusetts. These tree species include oak, ash, elm, alder, willow and maple. The caterpillars are also frequently spotted within leaf litter around the base of these trees. Experts claim that humans often encounter these caterpillars, as their preferred food source brings them into backyards, schools and parks. It is not uncommon for curious young children to handle a dagger moth caterpillar after finding one near outdoors. However, handling one of these caterpillars causes pain followed by an itchy rash. Dagger moth caterpillars gravitate into or near homes, particularly in crawl spaces and below decks, to find warmth during the winter months. During their winter stay within a structure these caterpillars mature into moths before flying out of homes and into the wild.

Have you ever picked up a caterpillar species with your bare hands?