Adults emerge in about seven days, mate, and females deposit eggs about three days after emerging. Damage is most evident in June and July and again in September and October. There are three or four generations each year. The alfalfa looper population is often reduced by a virus disease and several predators and parasites, but the populations of natural enemies may not be sufficient to reduce heavy infestations. Insecticides are commonly used to prevent damage by this pest, but fields should be sampled prior to treatment to establish the need for treatment.
Insecticides are much more effective against early instar larvae.
Take at least 100 sweeps in groups of 10 in different areas of the field and along the margins. See the Pacific Northwest Insect Control Handbook for a list of other registered insecticides on specific crops.