Answer: Grasshoppers are pests all over the world. They are voracious feeders that chew on just about anything. Some reach massive numbers if conditions are right, and they can strip fields of all vegetation in minutes. Grasshoppers leave large holes in many different crops. These holes not only make produce unsightly, but also rob the plant of surface area and resources that would otherwise be used for photosynthesis, thus reducing its growth potential.
Grasshoppers lay eggs in the fall in non-crop landscapes such as ditches, fencerows, and weedy areas and their eggs hatch in spring-summer. A grasshopper will only go through one lifecycle per year, but different species will hatch at different times during the year, which leads to a prolonged hatch period.
Because of this prolonged hatch period, I think it is best for you to repeat an application of Entrust within the next week or so to take care of the young grasshoppers you are seeing. By preventing these young grasshoppers (instars) from maturing and mating, you will reduce the number of eggs deposited in the ground this fall. I would spray at least once more and then monitor to see how many instars are present a week or so after the spray.
When it comes to tilling in the eggs, grasshoppers tend to lay eggs in undisturbed soil so most of the eggs will be deposited in untilled locations, such as you buffer strip. I am not sure you would want to till that grassy strip. The corn field itself is not an ideal location for a grasshopper to deposit eggs, so there are probably not many eggs in the field where you would be tilling (unless this is no-till production). Because of this I do not see cultivation as a very effective means of control for you.
I would focus efforts on spraying the grasshoppers in your buffer strip while they are in their instar stages and less than ½ inch long. This will reduce the number of eggs deposited this fall and reduce the hatch next year. You can then keep the buffer strip mowed in the spring so that when the new generation of grasshoppers hatch you can easily see them and begin to spray. Keeping your buffer strip mowed in the spring will also allow predators like birds to easily see the young grasshoppers and help you with the control.
ATTRA has produced a tip sheet titled Grasshoppers – Botanical Control Fomulations that should interest you. It discusses the use of neem, garlic, mint, and eucalyptus in managing grasshoppers.
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