Controlling Grasshoppers by Stephanie Suesan Smith, Ph.D.
Grasshoppers are once again so prevalent this year that they seem to be taking over the landscape. They are more prevalent in dry years because in wet years spring rains drown eggs and nymphs (baby grasshoppers). Since we have had very little rain, however, most of the grasshoppers have survived to cause us problems.
The best product to kill grasshoppers on a long term basis is NOLO bait. It contains a protozoan (Nosema locustae) that infests the grasshoppers. It kills the small ones and makes the bigger ones sick, so they do not eat as much or reproduce as much. It is completely specific to grasshoppers and will not hurt birds, pets, or other animals, even if they eat the dead grasshoppers. In addition, it will kill grasshoppers that feed on dead grasshoppers who are infected with the protozoan. NOLO bait is allowed in organic gardening.
NOLO bait is most effective when applied to nymphs and eggs. It does not do as much to large grasshoppers. It is also relatively slow to act, so a grasshopper can do a lot of damage before dying.
The other choice is to actively spray the grasshoppers. Spraying them with sprays containing carbaryl or permethrin are allowed on both vegetables and other crops and will kill the grasshoppers quickly. However, they do not have a long residual effect and must be reapplied frequently or after a rain. In addition, they kill other, beneficial insects as well as the grasshoppers. They are also not allowed in organic gardening.
Grasshoppers are one of the most difficult insect pests to control because they are so mobile. When you kill the ones on your garden or ornamental landscape, more just fly in and start munching away. For best results, remember to start control early in the season when the nymphs are small and to be persistent in your control efforts.