In a normal summer we can expect slugs, aphids, picnic beetles, Asian beetles, Japanese beetles and yellow jackets to eat our fruits and vegetables.
Due to the dry conditions this year, we can add grasshoppers to the list. They are taking large chunks out of my raspberry leaves and nibbling on the fruit.
Part of the Orthoptera family, which includes crickets and katydids, grasshoppers are some of the most familiar of all insects, with more than 550 species occurring in North America.
The Red-Legged Grasshopper is found throughout the U. S. and southern Canada, but is most common in the upper Midwest. The Migratory Grasshopper has an almost equally broad range but is not found in extreme southern Texas or Florida. The Two-Striped Grasshopper is found everywhere except in the Deep South. The Differential Grasshopper is present throughout the U.S. except in the extreme northeast, southeast, and northwest. It is most abundant between the Rocky Mountains and Mississippi River.
In other words, we are blessed with all four major species.
Females feed for about two weeks before laying their eggs. Eggs are laid in pods, often containing 50 or more eggs, and several pods may be produced. Each species has preferences as to where it lays eggs, with some choosing sun-exposed sites with compacted soil. Egg pods are typically inserted around the crown area or roots of plants.
Grasshoppers spend the winter as eggs, in an elongated pod containing 20 to 120 eggs. The eggs hatch in mid to late spring, depending on temperature, location, and species. If eggs are laid in scattered sites, the egg hatch can extend over a considerable period.
Nymph development typically takes five to seven weeks, during which time they pass through five or six stages.
Immature and adult grasshoppers are similar, but only the adults have fully developed wings. Wing pods are present on immature stages and become more prominent as maturity approaches.
Grasshoppers can show migratory behaviors. Nymphs sometimes march considerable distances. Adults may fly several miles, often at elevations of several hundred feet.
Physical changes may occur in populations about to move. For example, thinner body and longer wings are produced by two striped and migratory grasshoppers as they go into the more migratory phase.
For grasshoppers in the garden, the breeding site is often a nearby field, road ditch or empty lot. Because of their great mobility, grasshoppers can be among the most difficult insects to control.
Natural controls include birds and other vertebrates, blister beetle larvae and other insects. Grasshoppers can also succumb to diseases produced by fungi, protozoa, and nematodes. Weather conditions, particularly surrounding the period of egg hatch, are also critical to grasshopper survival, as adverse weather can inhibit egg hatch and kill young nymphs.
Grasshoppers are most easily controlled with insecticides when they are still immature and their location is restricted to breeding areas.
Effective sprays include acephate (Orthene), carbaryl (Sevin), and permethrin. These can be broadcast or applied in bands covering 50 percent of the area. Orthene, used according to directions, can be applied to pastures, roadsides and certain trees and shrubs. It cannot legally be applied to garden crops.
Grasshopper baits generally contain bran or a similar carrier mixed with carbaryl. Baits are easy to apply, are usually successful, and have little effect on beneficial insects. Disadvantages include slightly higher cost and less availability.