According to my entomology colleague, Joe Boggs, Horticulture Educator in Hamilton County, grasshoppers prefer dry summer conditions. This allows for great egg survival.
Grasshoppers lay their eggs in the ground and if the soil is wet for long periods of time, these eggs won’t survive. If the soil is dry, like it is right now (extremely dry in my landscape) the eggs survive.
Grasshoppers have incomplete metamorphosis as opposed to complete metamorphosis. Incomplete metamorphosis is when the insect’s life cycle consists of the egg, nymph and then the adult.
Complete metamorphosis is when the insect has the egg, larva, pupa and adult stage. A good example of this is butterflies and moths.
Grasshoppers are almost always associated with crops such as corn and other vegetables. During periods of heavy infestation, they will eat just about anything, including your landscape plants.
I have noticed that they really like ornamental grasses and ornamental corn. I have seen them destroy an ornamental grass planting.
In the later part of this season, when the adults are feeding, damage can be significant. We haven’t seen this type of grasshopper damage for several years. Since nymph populations are fairly significant right now, we may see it this August and September.
While I am not predicting a major outbreak of grasshoppers, I would suggest that you monitor your garden plants to see if you have them.
If you do find high populations of nymphs and are concerned about your landscape plants when the adults start feeding, you might consider spraying now. It’s a little easier to get the smaller nymphs.
Grasshoppers are a little difficult to control with sprays because they are so mobile, therefore, you spray on the foliage and that kills them when they feed. Or you can use dusts.
Products containing carbaryl (e.g. trade name Sevin) or permethrin (many trade names) are useful. As always follow directions and reapply if recommended on the label.