This time of year, it’s not uncommon to find gigantic black-and-white beetles when you’re outdoors. These are cottonwood borers, and they are fascinating insects because of their size and strength. Like all insects, their power is disproportionate to their size, and one of these bruisers could easily pull a Hot Wheels toy car. They are generally considered harmless to handle, though as this video closeup shows, they have large, strong jaws capable of cutting through bark and wood. I wouldn’t advise letting them bite you for the fun of it, but if you catch and hold them mid-body, they can’t reach you with their jaws.
These beetles actually come out in May and June, where they feed briefly on cottonwood and willow shoots before laying eggs. The females use their strong jaws to gnaw through bark of these trees near the ground line, and they mate and deposit eggs there. Larvae burrow into the wood near the root collar, and spend up to two years mining through the tree’s cambium layer. This cuts the xylem and phloem system carrying water and food between the tree’s roots and leaves, and when the larvae are present in sufficient numbers so that their wide mines overlap, it can kill the tree. The insects are therefore “pests” and some homeowners treat their trees to prevent injury.
From a wildlife standpoint, Cottonwood Borers are beautiful photo subjects. The long antennae constantly wave as the insects crawl or fly. Cottonwood Borers are the largest Kansas members of the insect family Cerambycidae, the long-horned borers. They can be nearly two inches long.
Watch for them whenever you’re outdoors. They are common in towns as well as naturally timbered areas. And their handsome coloration is unique and unsmistakable.