Issue: August 11,1997

Grasshoppers eating garden

How do you get rid of grasshoppers? They are devouring everything but my weeds. Most of the gladiolus flowers never got the chance to open. Now the grasshoppers are starting on my vegetables. Is it too late?

Grasshoppers are a yearly problem in New Mexico. If they don't cause problems for you in a given year, rest assured that someone is having problems. This year they are causing problems for many gardeners.

Since grasshoppers are capable of migrating from location to location, they are especially problematic. They begin in open land where the eggs were laid. First they feed on grasses and weeds, then when these are gone, they migrate to our gardens. Insecticides can be used to kill grasshoppers, but when used on a limited area such as a private garden or landscape, the effect is minimal. Insecticides will kill them, but new ones migrate in, eat the dead grasshoppers, then proceed to eat our plants. Because the bodies of the dead grasshoppers are eaten, it appears that the insecticide failed. Since new grasshoppers have migrated into the area, our gardens are still eaten. Application of appropriate pesticides to barrier plants around our properties can sometimes reduce the problem by killing many of the grasshoppers before they reach our vegetable and flower gardens. However, some will make it through to the gardens and require treatment there with insecticides or hand picking.

Some gardeners raise guinea fowl, turkeys, or other grasshopper eaters. These can then provide considerable protection from grasshopper damage, even though the fowl will do some damage to fruits and vegetables in the garden. If fowl are used, be sure to select insecticides carefully or, if you prefer, rely entirely on the fowl.

Some gardeners use Nosema locustae, a biological control agent for grasshopper control. Products with the Nosema are slow acting and relatively ineffective in controlling grasshoppers once they get larger. Besides, of the many different types of grasshoppers which infest New Mexico, the Nosema is effective with only a few. Of course, not all the grasshoppers we see in New Mexico eat our garden plants, many eat only weeds. Before treating for grasshopper control, be sure they are damaging your garden plants.

If you choose to use insecticides, be sure to choose a product labeled for use on the types of plants you have in the garden, and be sure it is for control of grasshopper problems. For your own safety, follow the label directions and be sure to note and follow the recommend harvest interval before harvesting and eating the treated vegetables. Wash all produce with clear water before eating it.

Marisa Y. Thompson, PhD, is the Extension Horticulture Specialist, in the Department of Extension Plant Sciences at the New Mexico State University Los Lunas Agricultural Science Center, email: desertblooms@nmsu.edu, office: 505-865-7340, ext. 113.

For more gardening information, visit the NMSU Extension Horticulture page at Desert Blooms and the NMSU Horticulture Publications page.

Send gardening questions to Southwest Yard and Garden - Attn: Dr. Marisa Thompson at desertblooms@nmsu.edu, or at the Desert Blooms Facebook.

Please copy your County Extension Agent and indicate your county of residence when you submit your question!