Be on the Lookout for Grasshoppers in Dry Weather

Published on: 08:53AM Aug 25, 2011

Roy Boykin, Ph.D.

Grasshopper infestations are cyclical; the population rapidly escalates for two or three years before it peaks and then returns for two or three years to normal population levels. Population decline occurs when the insects run out of food or when disease spreads throughout the swarms. But after the lull in reproduction, the numbers begin to mount again and the cycle continues.

In large numbers, grasshopper swarms can become particularly damaging, with some species known to be capable of eating up to seven times their body weight in vegetation daily. Therefore, when scouting for grasshoppers, look for round to ragged holes in soybean leaves that extend in from the leaf margins and between the veins. Grasshoppers may also feed on and damage soybean pods, often chewing through the pod tissue into the seed, which, according to Purdue University, may be a serious problem in dry years like this one.  

The 2010 season was labeled as a "peak" year for grasshopper infestations, with some states experiencing population levels not seen since 1980. According to entomologist Robert Wright of the University of Nebraska - Lincoln, numbers of adult grasshoppers last year are an indicator of the number of eggs laid. And the number of eggs that survive the overwintering stage will determine the grasshopper populations this year.
With dry weather and late planted soybeans, stay aware of the spread of grasshoppers to determine if your soybean fields could be at risk. If populations arise in your area, check your local university Extension to see if an insecticide application is warranted. If so, it is important to treat fields with a broad-spectrum insecticide before serious damage occurs. A broad-spectrum insecticide with the proven performance of three industry-leading technologies can offer fast knockdown and long-lasting residual control to create the best chance to protect soybean and optimize potential yield. 

Roy Boykin, Ph.D., Senior Technical Brand Lead, Insecticides, Syngenta 
Roy is responsible for the technical development, positioning and product life cycle management of insecticides for all business units in North America. Roy received his undergraduate education at the College of Charleston with majors in biology and business and received his master’s/doctorate degrees in entomology with minors in plant pathology and crop science from North Carolina State University.