Northern corn rootworm beetles are green to yellowish-green, sometimes almost tan, without stripes. They are about the same size as western corn rootworms (~ 1/6" to 1/4" long).

Tend to emerge a little bit later than western corn rootworm beetles, but the damage is the same. Also, the beetles feed on pollen of a wide variety of plants.

July, up to the first frost (generally common only in northern Nebraska).

Not validated, but probably the same as for the western corn rootworm.

Although not validated, probably the same as for the western corn rootworm. Some research shows that 1 western corn rootworm = 2 northern corn rootworm.

http://www.unl.edu/entomology/extension/crops/fieldcorn.shtml