Use A Sweep Net To Help Monitor Insects

A sweep net is a funnel-shaped net attached to a long-handled frame that is swept back and forth through crop foliage. Insects captured in the net are then counted, helping to determine whether or not enough insects are present to justify spraying. Standard sweep nets have a diameter of 15 inches, and can be purchased for under $40.

Muslin nets are stronger and will last longer than polyester nets, and are designed for field use, according to John Gavloski, Manitoba Agriculture and Food, Soils and Crops Branch, in an Internet backgrounder on selecting sweep nets for insect monitoring.  A muslin net with a porous, polyester tip is sometimes used. The polyester tip will eventually wear, but this porous material at the tip allows some visibility into the net, he says, and the porous tip also enables insects to be sprayed through the net with an aerosol insecticide, after concentrating them in the porous part of the net, for easy counting if necessary.

Two places to purchase sweep nets:

 BioQuip Products, 17803 LaSalle Avenue, Gardena, California 90248-3602, Phone: (310) 324-0620 Fax: (310) 324-7931, E-mail: bioquip@aol.com, Web page: www.bioquip.com.

•  Gempler’s, P.O. Box 270, 211 Blue Mounds Road, Mt. Horeb, WI 53572,
Phone: 1-800-382-8473 (orders); 1-800-332-6744 (customer service) Fax: 1-800-551-1128, web page: www.gemplers.com. Click on Crop Management, then click on sweep nets (under insect collecting tools and supplies). Gemp-ler’s also has an online tip sheet on how to use a sweep net at www.ipmalmanac.com/tipsheets/tip5.asp.

Sweep nets work best in low bushy or grassy plants like alfalfa, soybean or small grain, says NDSU entomologist Gary Brewer. “I wouldn’t suggest their use in sunflower. Use in sunflower will not collect many insects, will break plants, and probably tear the net,” he says.