Make sure you are watching your pastures, lawns and gardens. I am getting a few phone calls on grasshopper damage.
Grasshoppers are among the most widespread and damaging pests in Texas.
There are about 150 species of grasshoppers in the state, but 90 percent of the damage to crops, gardens, trees, and shrubs is caused by just five species.
The main factor affecting grasshopper populations is weather. Outbreaks, or exceptionally large populations, are usually preceded by several years of hot, dry summers and warm autumns. Dry weather increases the survival of nymphs and adults.
Warm autumns allow grasshoppers more time to feed and lay eggs. Grasshoppers have a high reproductive capacity. The female lays an average of 200 eggs per season, and sometimes as many as 400 eggs.
Grasshoppers deposit their eggs 1⁄2 to 2 inches below the soil surface in pod-like structures. Each egg pod consists of 20 to 120 elongated eggs cemented together. The whole mass is somewhat egg- shaped.
Egg pods are very resistant to moisture and cold and easily survive the winter if the soil is not disturbed. Grasshoppers deposit eggs in fallow fields, ditches, fencerows, shelter belts and other weedy areas, as well as in crop fields, hay fields.
Young grasshoppers are called nymphs. They look like adults but are smaller and have wing pads instead of wings. Nymphs go through five or six developmental stages and become adults in 40 to 60 days, depending on weather and food supplies.
Biological Control Another natural enemy is a protozoan, Nosema locustae. Its spores have been incorporated with bran to make insecticide baits such as Semaspore, Nolo Bait or Grasshopper Attack. These baits kill some nymphs but almost no adults, though infected adults lay fewer eggs. Baits act too slowly and kill too few grasshoppers to be useful for immediate control.
Other natural enemies include nematodes called hairworms and insects that feed on grasshoppers, such as the larvae of blister beetles, bee flies, robber flies, ground beetles, flesh flies and tangleveined flies. Birds (quail, turkey, larks, etc.) and mammals also eat grasshoppers, but have little effect on large populations.
Monitoring Populations
Farmers and ranchers should start watching for grasshoppers early in the season and begin control measures while grasshoppers are still nymphs and still within the hatching sites (roadsides, fencerows, etc.).
Treating grasshoppers early means 1) having to treat fewer acres and use less insecticide, 2) killing grasshoppers before they cause extensive crop damage, and 3) killing grasshoppers before they can fly, migrate and lay eggs.
Also, smaller grasshoppers are more susceptible to insecticides than larger ones.
You can estimate the size of a grasshopper infestation by surveying for nymphs or adults with the “square foot method.” Count the number of grasshoppers that hop or move within a square foot area.
Then take 15 to 20 paces and sample another square foot area.
Make 18 samples in all. Then add the numbers from each sample and divide the total by two to obtain the number of grasshoppers per square yard.
If most grasshoppers you see are first to third instar (wingless and generally less than 1⁄2 inch long), divide the number by three to give the adult equivalent.