We have received a number of calls on grasshoppers recently. Permethrin
(numerous trade names) is a good choice for vegetable crops because it is
labeled for a wide variety of vegetables. However, keep in mind that hoppers
can reinfest an area relatively quickly. Many times gardeners have not had
an insecticide failure, but a reinfestation. Carbaryl
(Sevin) can also be used for grasshopper control but can lead to mite
outbreaks as it is very toxic to mite predators.
We often have gardeners who are interested in organic controls. Nosema
locustae, a protozoan, is the active ingredient in a number of products
including Semaspore, NOLO Bait, HopperStopper and Grasshopper Attack.
These products are selective and will affect only grasshoppers. This is a
trait many gardeners find attractive. However, Nosema locustae products may
not be as effective in garden situations as they would be under large-scale
rangeland conditions due to potential reinfestations from outside the
treated area. Also, these products have other potential
– They are most effective against nymphal rather than adult grasshoppers.
Also some grasshopper species are less susceptible than others.
– Kill can take 3 to 6 weeks after ingestion.
– These baits are perishable and should be kept refrigerated until use.
Pay attention to the expiration date.
As mentioned above, reinfestations of uninfected grasshoppers can occur.
These products are not effective against adults. Try to treat the nesting
area when hoppers are small and populations are concentrated.
Nosema locustae products are allowed in certified organic crop production.
Poultry including turkeys, guinea hens and chickens have also been used to
help control grasshoppers.
Regardless of method used, the trick is to treat early before the population
has matured. Young nymphal stages are much easier to control than adults and
are also much less mobile.
By: Ward Upham