Black Locust Worm

The black locust is a fast-growing tree with long thorns on its trunk and branches.   In the spring it has large dangling clumps of white blooms that fill the air with a heady perfume.  In the late summer and early fall, seed pods form.  At maturity the seed pods are about an inch wide and about ten inches long.

The Black Locust Worm is a large segmented worm-like creature that resembles the seed pod of the black locust.  These worms are abundant in areas where the black locust grows.  During the spring and summer, the worm burrows beneath the forest floor, eating dirt and organic materials and leaving mineral-rich soil behind.  They consume dead and damaged bits of roots, helping to keep trees and other plants healthy.  Their burrowing also loosens and aerates the soil, bringing water, air, and nutrients to the roots.

In early autumn, when the seed pods clutter the ground, the worms come to the surface.  They die, and their bodies dry and curl until they are nearly indistinguishable from the seed pods but, dormant within them, are their eggs.

Deer, birds, and a variety of other animals eat the seed pods.  They also eat the worms.  Inside the animal, the eggs hatch into larvae, burrow into the flesh of the animal, and begin to feed.

The larvae don’t usually kill their hosts outright, but the animals are so weakened that they often succumb to the winter or to predators.

The worms do not need to be ingested to be dangerous.  The eggs will also hatch if the ambient temperature rises above 85o F (30o C).  Animals, or unwary travelers, who bed down on the seed pods are warm enough that the eggs will hatch and burrow beneath their skins.  The larvae secrete a powerful anesthetic, numbing the skin of their hosts, and it may be several days before the host notices anything amiss.

The larvae begin fairly small, perhaps a quarter inch in length.  They feed for about two weeks and when they’ve grown to about two inches they burrow their way out.  Once they reach the forest floor, they dig straight down until they are below the frost line.  There they pupate and hibernate through the winter.  In early spring they shed, and the adult emerges.  They come together in large clumps to mate, and then the cycle begins again.



Creative Commons License This work by Jean Headley is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Photograph by Jean Headley, 25 November, 2017.

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