Tiny Bison?

Two-marked treehopper - Wikimedia

While looking for leaf galls I noticed a small 5mm white speck on the under surface of a tree leaf, apparently dried up and dead.  Under magnification it resembled a tiny white bison, frozen in time.  With a plunge into INaturalist and Google I came up with an answer.  This is the final nymph of a twomarked treehopper, Enchenopa binotata (EB).  EB is a species complex made up of multiple species, often identified by their host plants.  The adult is only 7-9 mm long.  As usual, a deep dive into the tiny critter's life reveals interesting quirks.

Like many tiny insects that we overlook, EB is mainly discussed as a minor pest.  Most websites focus on the minor cosmetic damage they cause to a tree in our yard.  

"Twomarked treehoppers cause damage to hop tree or wafer ash, Ptelea trifoliata, black walnut, butternut, black locust, viburnum, redbud and bittersweet."  A more broadminded nature site says "This insect rarely causes enough damage to warrant control, even though the insect itself is abundant."

The nymphs sucking up the sap go through 5 instars before reaching the "white bison" stage if found.  The feeding results in honeydew which allows the fungus sooty mold (mycelium is black) to grow and turn the plant blackish. This in turn draws ants and other insects that lap up the sweet honeydew, all part of the food web.  Egg laying may cause minor slits in the bark.

 

The University of Illinois Urbana describes its life cycle.

Nymph stages

"The twomarked treehopper will overwinter as an egg under bark. Newly hatched nymphs move to the tips of the new shoots where they extract plant sap in mass. The nymphs are brown to dark gray. After a little more than a month, the twomarked treehopper becomes an adult. 

As adults, they often line up in a row on the new shoot. Females lay eggs until August. However once egg laying starts, it will continue till the adult is frost killed. The female treehopper has a saw like ovipositor. She uses this to make a small cut in the twig. The eggs are forced through the narrow cut so that they are left under the bark. Once the egg laying for the individual cut is completed, the adult female seals the cut."

Males hookup with females by seismic communication, "substrate-borne vibrations on the stems, petioles, and leaves of their host plants that travel throughout the plant."  It is hard to imagine this tiny creature shaking a stem to make a sound but you can here it in this Wikipedia link. 

Before and after - Linda Williams MN

For more on our Missouri treehoppers, check out this MDC link.