In addition to the beating our pastures took last year, an indirect effect of the record-breaking drought is this season’s grasshopper population. Grasshoppers are a threat every year, but can be very destructive in outbreak years. Their voracious feeding habits are legendary. In proportion to their body weight, they consume grasses eight times faster than beef cattle.
“High grasshopper populations are tied to hot, dry weather for a number of reasons,” said Dr. Chris Sansone, AgriLife Extension program leader for entomology. Drought damaged range and pasture grasses create areas with little to no grass. Hatching grasshoppers use these areas to warm up in spring. The open areas also slow the insect fungus that normally controls grasshoppers. But grasshoppers, being cold-blooded, also thrive with warmer temperatures. Hot weather means their metabolisms run faster, so they eat more and grow faster. In addition, the grasshopper hatch came early this year because of the relatively warm spring. In a normal year, treatment should begin in mid-April, but this year treatment should have begun mid-March to the first of April.
The best way to control grasshoppers is to spray when the hatches first start, when control is very inexpensive. Insecticides like Dimilin, which prevents insects from molting, must be sprayed when the grasshoppers are young, before they form wings.
But what usually happens is that, come June and July, there are large grasshopper numbers leaving their habitat in search of food, resulting in constant invasions that must be sprayed every 7 to 10 days. Insecticides available for grasshopper control have limited residual activity and will not kill new arrivals after several days. Insecticides start to break down as soon as they are mixed with water and exposed to sunlight. Thus, in the summer, most insecticides will work for about 24 hours.
For beef cattle producers, grasshoppers compete with cattle for available forage. Thus, ranchers are encouraged to scout fields. The economic threshold for grasshoppers is 7 to 10 insects in a square yard. If an infestation is not handled properly or in time grasshoppers can devastate forage production.
“Their presence, coupled with the ramifications from drought conditions and warmer temperatures this year, can greatly decrease a producer’s ability to effectively utilize pastures for grazing,” said David Annis, soils and crops consultant at the Noble Foundation.
It is also a good idea to work with neighbors when treating for grasshoppers. This joint effort will lengthen the life and effectiveness of treatments.
The best control option for homeowners trying to protect their lawn is to prevent them from entering by treating the surrounding area – the wider the border, the more effective the control.
There are several insecticides on the market. Of these, some are safe to be used on vegetable gardens. The most important thing is to read and follow label directions.
There is also a list of plants developed by extension horticulturists John Cooper and Stan Lovelace which are not preferred by grasshoppers. These plants include Crape myrtle, Dwarf yaupon, Dwarf Mexican petunia, Lantana, Moss rose and Verbena. For the complete list, contact Missy at the extension office.
For more information about these topics contact the AgriLife Extension office, Clay County at (940) 538-5042.