Grasshoppers Abound

As you may have noticed lately, grasshoppers populations have increased substantially. They may have even increased to an economically damaging level at your nursery. The eastern lubber grasshopper is especially prevalent during this time of the year. These are the large ones that practically knock you down when they bump into you. I have scanned through some of the fact sheets on the IFAS EDIS (Electronic Data Information Source) to find some information on what you can do to prevent lubber grasshopper damage to your plants. The following paragraphs are taken directly from (EENY-006 Eastern Lubber Grasshopper, Romalea microptera (Beauvois) (= guttata (Houttuyn)) (Insecta: Orthoptera: Acrididae) C. W. Scherer and J. L. Capinera, originally published 1996, revised 2008) here is the factsheet if you would like further information http://edis.ifas.ufl.edu/in132

“Adults of Romalea microptera exist nearly throughout the year in Florida with their numbers dwindling during the fall and winter period. They have one generation per year, with eggs beginning to hatch in February in South Florida while the rest of the state usually doesn't see this species until March. Eastern lubbers, like all grasshoppers, grow through successive stages after molting. These stages (instars) are referred to as nymphs. Lubbers have a total of five instars before molting into the adult stage. The length of these instars vary slightly but average 15 to 20 days each. The highest number of adults can be observed during the months of July and August.

Females will begin laying eggs during the summer months. After mating, females use the tip of the abdomen to dig a small hole into a suitable patch of soil. Usually at a depth of about two inches, she will deposit up to 50 eggs contained within a light foamy froth. Each female will lay from one to three egg masses. These eggs will remain in the soil through late fall and winter and then begin hatching in March. The young grasshoppers crawl up out of the soil upon hatching and seem to congregate near suitable food sources. Lubbers are often found in damp or wet habitats, but seek drier sites for egg-laying.

Populations cycle up and down, possibly due to the action of parasites. The tachinid fly Anisia serotina (Reinhard) attains high levels of parasitism, sometimes 60-90%

The size of the eastern lubber grasshopper is a little misleading when one considers they require far less food material than most of the more injurious species of grasshoppers that are only one-third as large or smaller.

Grasshopper abundance can be regulated through management of the vegetation. If you deprive grasshoppers of their favored food, often they will leave or perish. Keeping the vegetation mowed is very helpful, as short vegetation does not often support grasshoppers
Lubber grasshoppers will often develop initially in moist areas around ponds and irrigation ditches, then later migrate to homes, yards, and crops. Rather than waiting for the grasshoppers to come to you, it is often best to take the battle to them. So check potential breeding or feeding sites for signs of grasshoppers. The young grasshoppers remain clustered in groups, but as they get older they are more likely to be solitary.

Grasshoppers are not easy to kill, even with insecticides, once they become large. Among the insecticides that will kill lubber grasshoppers are carbaryl, bifenthrin, cyhalothrin, permethrin, and esfenvalerate (note: these are the technical names, which appear in the 'ingredients' section on the label). You likely will have to apply the insecticide directly to the insects; the small amount of insecticide residue remaining on sprayed plants may not adequate to kill the grasshoppers.”

Along with chemical control there are a few biological control options that can be used. Nosema locustae, a naturally occurring protozoan that causes disease and death in crickets and grasshoppers and sold under the trade name Nolo Bait® and Grasshopper Attack®. This biological control is best used when grasshoppers are in the younger stages of maturation. With ingestion of the protozoan, the grasshopper reduces feeding activity and egg laying and between 60 to 90% will die. The next generation of grasshoppers can become infected with egg contamination from adult female grasshoppers. Derived from Eny-275. Microbial Insecticides. R. Weinzierl, T. Henn, P. G. Koehler and C. L. Tucker. http://edis.ifas.ufl.edu/pdffiles/IN/IN08100.pdf

The fungus Beauveria bassiana is yet another biopesticide registered for grasshopper control. This is a soil fungus that has a broad spectrum of insect control. It is sold under the trade name BotaniGard®. The spores of this fungus penetrates the insects cuticle and consumes it from the inside.

Remember to decide if the level of economic damage is sufficient to warrant control measures. Culturally, there can be some control of grasshoppers with disking in the winter time to expose eggs and mowing in the spring and summer to remove food sources for the grasshoppers to eat.