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Grasshoppers, What Can You Do?

posted May 15, 2011, 4:48 PM by Bob Whitney   [ updated Jun 3, 2011, 8:36 PM ]
    Grasshoppers are among the most widespread and damaging pests in Texas. Approximately 150 species of grasshoppers are known to exist in the state; however, the following five species cause 90 percent of the damage to crops, gardens, trees and shrubs: Differential, Red-legged, Migratory, Two-Stripped and Packard.
    These insects cause some damage every year but become very destructive during outbreak periods.  Why in this year are there some many?  Weather is the main factor affecting grasshopper populations.  Outbreaks are usually preceded by several years of hot, dry summers and warm autumns - just what we had last year.  Dry weather increases nymph and adult survival.  Warm autumns allow grasshoppers more time to feed and lay eggs.  Cool, wet weather slows nymph development, reduces the number of eggs laid, and increases the incidence of diseases.  Grasshoppers have a high reproductive rate and the female can lay up to 400 eggs in a favorable year such as last year and with the mild winter many eggs survived to be a problem now.
    Grasshopper eggs are laid ½ to 2 inches beneath the soil surface in pod-like structures.  Each egg pod consists of 20 to 120 elongated eggs securely cemented together and the whole egg mass is somewhat egg-shaped and covered with soil.  These egg pods are very resistant to cold and moisture and will survive if the soil is not disturbed.  Grasshopper egg hatch normally begins in late April to May.  There are usually 5-6 nymphal stages and the length of time from egg to adult is 40-60 days.  There is only one generation of grasshoppers produced per year.
    Grasshopper have many natural enemies that help control populations.  A fungus, Entomophthora grylli, often causes locally high death rates.  This fungus is much more active in wet, cool weather which we haven’t had.  When the grasshopper is infected with this fungus he goes to the top of a weed and grasps the plant in a death embrace with front and middle legs while the hind legs are extended and dies in this position.  The fungus develops spores in this dead grasshopper that then affect other grasshoppers.  This of course takes time to work.
    Chemical control is possible but difficult because the grasshoppers move so much.  Keeping all weeds and grass mowed around the place helps keep them out of gardens but even then they can become so numerous that something has to be done.  For gardens, trees and shrubs,  Malathion and Sevin are recommended.  Use a hose end sprayer for total coverage.  For Commercial Agriculture choices include several chemicals but for all around use Dimilin is the best.  Dimilin is a growth regulator and very effective at low rates and price!!

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