During the last weeks of August and the beginning of September, Thunderbird High School was hit with a swarm of green caterpillars. The school grounds were covered in goop, guts, and the few caterpillars trying to escape with their lives. Throughout the halls you heard screams of scared students and groans of disgust as herds of people stepped on the insects, resulting in caterpillar remains inhabiting bottoms of shoes.
What exactly are these peculiar creatures? They are larvae belonging to a species of moth called the White-lined sphinx. White-lined sphinx color variation depends on the region. In the case for Thunderbird High School, the larvae were roughly 3 ½ inches, green with black and yellow spots, and a little horn on the tip top of the heads. Typically, the larvae and moths do not survive winters but do migrate up south in North America during spring. Every year southern Canada and Central America experience multiple generations but are mostly seen in warmer climates.
It was not just a random phenomena, “Larvae can occasionally occur in tremendous numbers and can move in hordes in search of food, consuming entire plants and covering roadways in slick masses,” says Susan Mahr, Master Gardener Program Coordinator at University of Wisconsin-Madison. This explains the abrupt invasion of caterpillars.
Thunderbird High School happens to be right by Thunderbird mountain, and according to the National Park Service (NPS), “The larvae burrow into the soil when they go into the pupal stage, where they remain for 2-3 weeks before they emerge as adults,” making the ground perfect for these little critters to pop up everywhere. Experts describe the adult moth as “… a large, stout-bodied moth with a furry brown body crossed by six white stripes,” says Mahr.
Given these sentiments, get ready for green bugs with horns to turn into moths, but have no fear! These green little guys are not poisonous. When next year comes, be on the lookout for the next caterpillar takeover.