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Past Articles Library | Organic Pest Control | Grasshoppers

GRASSHOPPERS
(Acrididae)

The word "Grasshopper" has become a catch-all name for members of the Locustidae and Acrididae family, which includes locusts, grasshoppers, crickets and katydids. These insects are extremely destructive and difficult to control because they are migratory.

DESCRIPTION

Adults are brown, yellow, or green and 1 to 2 inches (2.5 to 5 cm) long, with leathery forewings and enlarged hind legs for jumping. Many have brightly colored underwings. Nymphs are similar to adults but are smaller, and have short or rudimentary wings.

LIFE CYCLE

Grasshoppers have three life stages: egg, nymph (young adult), and adult. Control methods vary with life stage. In late summer, females lay elongated masses of eggs in burrows in the soil. Eggs hatch in the spring, and nymphs develop for 40 to 60 days, then molt into the adult stage. Adults feed until killed by cold weather.

PLANTS MOST AFFECTED

Adult grasshoppers will any plant, but they primarily like cereals and grasses.

DAMAGE

Large scale economic damage is usually to field crops, but on occasions when large grasshopper populations build up, they can devastate large areas and garden plants in outbreak areas will also be damaged.

MEANS OF CONTROL

Prevention:

For regular prevention, and not during a huge outbreak, natural enemies do a good job. Ground beetles, predatory flies, birds, parasitic nematodes will usually suppress grasshopper populations.

Building birdhouses and planting cover to attract birds is very helpful.

Cover garden plants with floating row covers.

Control:
Grasshoppers are difficult to control because they are migratory. You could kill them all today and they will move in from somewhere else tomorrow. There are, however, several organic approaches to controlling this pest. The key word here is control. It is impossible to completely eradicate the species from your yard.

There are a couple of sprays and baits that are made of naturally occurring grasshopper diseaes (Nosema locustae or Beauvaria bassiana) which are good for use over large areas.

Nosema locustae
Nosema is a biological control, a single celled protozoan, that infects all stages of developing grasshoppers, mole crickets, Mormon and black field crickets. Nosema when ingested creates a disease that is specific to these pests. It will not harm any other living species.

Timing is everything. You have to use it when the grasshoppers are in their nymph stage. The ideal time is when they are 1/4 inch (.6 cm) long. The spore causes blood poisoning, which brings on death. Dead grasshoppers are eaten by live grasshoppers who are then infected. It can carry through the season this way and even last year to year by over-wintering on an infected egg pod. One pound (454 g) covers one acre (405 hectare).

Grasshoppers typically lay eggs in Southern exposure locations in hilly, sandy soil. As they hatch they will begin to travel to their food source (your garden or farm). Head them off by applying Nosema in swaths as a barrier about 1 foot (30.5 cm) wide, or by generally broadcasting product in and around area to be protected. Grasshoppers will begin to feed on spore-infected bran and immediately stop feeding and become sick. They will die either from the disease or will be cannibalized by other hoppers.

Nolo Bait
Nolo Bait is a wheat flake that has been spiked with a grasshopper disease, Nosema locustae. It doesn't harm any other insects except for Mormon crickets and perhaps other everyday crickets. When properly applied, the grasshoppers eat the Nolo and get sick. Tomorrow's grasshoppers cannibalize the sick ones, spreading the disease through the population. Nolo Bait is probably most recommended for homeowners with some acreage, unless whole blocks or neighborhoods in the city could get together for a concerted anti-grasshopper effort. Because of the grasshoppers' sheer numbers and mobility, Nolo Bait is most effective when used over larger areas.

Kaolin clay
There is a relatively new control called Kaolin clay. One to two cups (240 to 480 ml) of the powdered clay is mixed with one gallon (3.8 l) of water with about one teaspoon (5 ml) of soap, such as a mild dishwashing soap or Dr. Bronner's soap (from health food stores). To make mixing easier, the Kaolin clay should be slowly added to a cup or two (240 to 480 ml) of water first to make a paste (with the soap), and then added to the rest of the gallon (3.8 l) of water. This mixture should be sprayed onto all leaf surfaces. The object is to have a white film on the leaf that repels the grasshoppers. This may require more than one application, depending on the concentration of clay in the spray.

Diatomaceous Spray
Mix one cup (240 ml) of diatomaceous earth with one gallon (3.8 l) of water along with two tablespoons (30 ml) of blackstrap molasses. Spray this onto the plants. Diatomaceous earth looks like talcum powder, but to the insects it is like broken glass.

Neem oil
Neem oil from the Neem tree in Australia can be used as a repellent. It works in several different ways. It is a repellent, a feeding inhibitor, deters egg-laying, and retards growth.

Pesticidal soaps
Pesticidal soaps may also be used. It is the fatty acids in the soaps that make them work. When the soap touches the outer body of the grasshopper it slowly begins to dissolve this outer membrane. This causes dehydration and death. You need to be careful when using this on your plants since it can do the same thing to your plants that it does to grasshoppers. Test a small portion of the plant first before your treat the whole plant.