The caterpillars are coming!

Background: Every year, caterpillars come out in droves to feast and prepare for the transformation into butterflies and moths. This occurs from spring to autumn. Caterpillars appear defenseless but that is not the case. There are thousands of different species in Michigan alone. A few species have urticating hair and a few have venom-containing hairs similar to hypodermic needles. The result of contact with these defense mechanisms includes local itching, erythema, and edema. Absolute numbers of caterpillars depend on environmental factors such as food source and predators. The Michigan Poison Center has seen an increase in the calls related to caterpillar exposures over the past 14 years. Methods: This is a retrospective chart review of the Michigan Poison Center data on calls for caterpillar exposure from 2005 to 2019. Yearly totals were tabulated. Results: Over the 14 years through 2019, there has been an increase in the calls related to caterpillar exposure with 2019 being the highest at 55 calls. Year 2005 had 13 calls followed by a 7-year lull with call volume ranging from 3 to 8 per year. Call volume began increasing yearly starting in 2014. Though most calls do not contain adequate descriptors to speciate, they report minor, local effects on the hands or arms consistent with caterpillar dermatitis. Serious cases included those that had generalized urticaria as well as those who had oral contact with edema involving the upper airway. Conclusion: As climate changes and human encroachment of habitats continue, wildlife exposure frequency changes as well