Gardening Articles: Care :: Pests & Problems

Managing Grasshoppers

by Whitney Cranshaw

Grasshoppers are found throughout North America, but are most problematic in the High Plains and Rocky Mountain states, especially in areas where rainfall is between 10 to 30 a year.

Family: Acrididae (short-horned grasshoppers)

Size and color: Most are about 3/4 to 1 long, although larger species occur. Colors vary; greenish, yellow-brown, or gray are the most common.

Crops affected: Essentially any garden plant, as well as most trees and shrubs.

Prevention and Controls: Take measures before migrations into gardens occur. Treat breeding sites with insecticides or the biocontrol Nosema locustae. Exclude grasshoppers with row covers or screens. Plant green buffer zones away from food and flowers where they can land to feed. Use insecticides in the buffer or enclose it with fencing and let poultry feast on hoppers.

No insects have been recognized for so long as capable of devastation as grasshoppers, the locusts" of Biblical plagues. (In America, locust is sometimes used inappropriately to describe a very different insect, the periodical cicada, whose emergence in large numbers alarmed English settlers in the Northeast.)

Few garden pests have such all-inclusive tastes or can be so aggravatingly difficult to control as grasshoppers. For one thing, they are highly mobile, capable of moving hundreds of feet a day, and sometimes much more. For another, there are a great many species. Fifty or more kinds of grasshoppers may occur in some of the "hopper-rich" western states, and the populations of any one of these types may be on an upward cycle during a given year. Though many species limit their feeding to non-garden plants, such as grasses and clovers, others find most vegetables, flowers and even trees and shrubs to be very acceptable snacks.

Almost all the serious garden pests are found within the genus Melanoplus, which includes the redlegged grasshopper (M. femurrubrum), twostriped grasshopper (M. bivittatus), differential grasshopper (M. differentialis) and migratory grasshopper (M. sanguinipes). All of these spend the winter within an egg pod laid an inch or so below the ground. The egg pods are deposited about three inches deep in the soil in late summer and early autumn, usually in dry, undisturbed areas outside of tilled fields or garden plots.

Eggs hatch in late spring or early summer. The young hoppers (nymphs) are wingless and, of course, smaller in size, but generally resemble the adult insects. They feed and grow over a period of about two months before reaching the adult stage, at which time they become capable of flight and are sexually mature. Migrations accelerate as this stage is reached, which often coincides with drying of grasses and other early-season food plants. It's then that the insects tend to move to the relative "oases" of irrigated yards and gardens. Grasshoppers may continue to feed and lay eggs until hard frosts finally kill them off for the season.

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