Unspoken Truths About Pests: Grasshoppers
Drought provides perfect environment for this destructive insect
Nearly 400 species of grasshoppers inhabit the 17 western states. They feed on grasses and weeds and often move to cultivated crops.
“Because grasshoppers move into cropland generally from untilled areas surrounding crop fields, scout and, if necessary, treat these adjacent untilled areas first,” says Bob Wright, University of Nebraska Extension entomologist.
In corn, grasshoppers feed from the outer edges of leaves inward. They can eat stalks and ears. They attack fresh silks, reducing pollination and often cause the ears to be blank or only partly filled.
Verify your grasshopper threat, Wright says, by using the square-foot method in field borders:
- Randomly select an area several feet away and visualize a square-foot area for that spot.
- Walk to this spot while watching this square-foot area and count the number of grasshoppers you see in or jumping out of this area.
- Repeat this procedure 18 times and divide the total number of grasshoppers by two.
- This will give you the number of grasshoppers per square yard.
To assess grasshopper densities within fields — where grasshopper density will be lower — use the same method except visualize and count the grasshoppers in a square-yard area. Average your 18 estimates to calculate the number of grasshoppers per square yard.
If you count more than 40 grasshoppers in field borders, you need to treat the pest, according to the University of Nebraska. Within fields, the threshold is 14 or more. Numerous insecticides are labeled and effective for grasshopper control on various crops.
Your goal, Wright says, is to control grasshoppers while they are concentrated in field borders and before they become adults and have fully developed wings. Be aware, grasshopper damage can occur anytime during the growing season.
Fast Facts About Grasshoppers
- Nearly 400 species of grasshoppers inhabit the 17 western states.
- Each species of grasshoppers produces their own unique sound and language.
- Depending on the species, grasshopper eggs range from 4 mm to 9 mm long and may be white, yellow, olive, tan, brownish red or dark brown.
- Adult grasshoppers live around 51 days.
- Even light grasshopper infestations (around 7 per square yard) in a 10-acre hay field will eat as much hay as a cow; 17 hoppers per square yard in a 40-acre hay field will eat a ton of hay a day.
Sources: USDA, Field Guide to Common Western Grasshoppers, Purdue University
