Alfalfa Hay Pests

Stuart Reitz
March 2021

In all cases, follow the instructions on the pesticide label. The PNW Insect Management Handbook has no legal status, whereas the pesticide label is a legal document. Read the product label before making any pesticide applications.

Note: Products are listed in alphabetical order and not in order of preference or superiority of pest control.

Pesticide resistance: Modes of action are important criteria in selecting insecticides so as to prevent the development of resistance to insecticides. Rotate chemicals with a different mode-of-action group number, and do not use products with the same mode-of-action group number more than twice per season. For example, pyrethroids have a group number of 3A; chemicals with a 3A group number should be alternated with chemicals that have a group number other than 3A. Mode of action groupings are assigned by IRAC (Insecticide Resistance Action Committee). For additional information, see their Web site at