Caterpillars for the Birds

Spring is here! All the signs are evident, including walking into caterpillars hanging from trees by slender threads (which happened to me last week). These danglers are often members of the Geometridae family, also known as inchworms or loopers. I love that their Latin name means “measures the earth.” The distinctive gait of these caterpillars makes it seem like they are taking their measuring duties very seriously. First, they deploy their front feet, and then, unlike other caterpillars with intermediate appendages, they pull forward their rear feet. This causes them to arch their bodies in that characteristic manner. Unsurprisingly, this onset of caterpillars coincides with the first flush of spring leaves, a buffet for these newly hatched critters.

Inchworm (Geometridae)

Inchworm (Geometridae).
Photo Credit: Matt Bertone, NCSU
https://cals.ncsu.edu/entomology-and-plant-pathology/people/maberto2/

Why am I so happy to see this abundance of caterpillars? Caterpillars are often perceived as pests, and some gardeners immediately spring into action with a chemical response. However, we must pause and think holistically about the caterpillar’s role in nature. The spring explosion of caterpillars is perfectly timed to feed baby birds. The number of caterpillars necessary to accomplish this is astonishing! According to entomologist Doug Tallamy, a single chickadee clutch requires at least 7000 caterpillars to fledge. While the adults are still at your feeders for themselves, they must also source this soft-bodied protein for their offspring. In fact, 96% of all North American land birds feed their young with insects. So, when you have the urge to grab that pesticide bottle, remember the caterpillars will soon be new birds or a new moth, ready to start the cycle again.

Source:

  1. Cornell Lab of Ornithology Caterpillar: It’s What’s for Dinner

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