Nationwide scout for alfalfa weevil and other pests
She said it can be easily recognized by a distinctive triangle on the back and large bulging eyes. Nymphs are green and similar to adults but lack wings. They look like large aphids from a distance. Both nymphs and adults of lygus bugs have piercing and sucking mouthparts allowing them to feed on plant sap. The saliva of these bugs also causes necrosis of plant tissue at the feeding spot. Lygus species are severe pests in seed alfalfa and many other field crops but not a serious concern in forage alfalfa.
Chirumamilla said that neither the alfalfa caterpillar nor lygus bug are considered serious pests of forage alfalfa. "Presence of these might actually help feeding the natural predator and parasitoid populations," she said. "However, alfalfa caterpillars can be damaging in case of high populations. Scouting frequently with a sweep net and keeping an eye on insect species and populations is always a safe and secure practice."