They tend to stay in weedy areas where there is an abundance of grasshopper eggs since the larval stages love this delicacy. The adults damage the crops, but usually they don't gather in great enough numbers to notice the damage. Adults are slender oblong beetles with yellow stripes in some form. Larva are usually found in several stages and all stages have 3 upper body legs. The pupa stage is a stage of darkening, starting with the eyes.
Eggs are oblong and yellow.
They chew on just about any vegetable especially vine and root crops. They are mostly foliage feeders but will eat flowers as well. Not only do they eat your plants, but they leave behind black stringy substances. Treatment after the fact will kill the insects, but it's hard to save the crops once they have been completely defoliated. A preventive measure may be to use rotenone or other organic powders and sprays before you have a problem.