Minor Alfalfa Insects

 

Variegated Cutworm   (Peridroma saucia)

 

Nocturnal worm that can severely damage alfalfa seedlings or reduce new growth in established fields. Adult worm is approximately 2 inches with yellow diamond shaped spots down the middle of back. 

 

Caterpillars

 

 

Caterpillar infestations are generally kept in check by natural parasites and/or cutting regimes. Severe infestations may require chemical control, since like most minor pests, resistant varieties are not available. The following is a list of the more common caterpillars and their descriptions.

 

 

Alfalfa caterpillar (Colias eurytheme)

The adult is the common yellow or white butterfly often seen in alfalfa fields. Caterpillar is green with a white strip on both sides of body.

 

 

Beet armyworm (Spodoptera exigua)

 

 

Caterpillar is green to purple-green

 

 

Western yellow striped armyworm  (Spodoptera praefica)

Caterpillar is black with orange stripes on sides

 

 

Alfalfa Looper (Autographa californica)

Caterpillar is dark green with darker strips down back and sides

 

 

Thrips(Frankliniella spp.)

 

 

Very small insect, that feeds on young leaves and buds. Damage to developing leaves results in wrinkled or distorted leaves. Generally not considered economically important in hay fields, but leaf symptoms are very common in alfalfa fields.

 

 

Plant bugs (Lygus spp.)

 

 

  

Often seen in alfalfa hay fields but are only considered serious pest in alfalfa seed production.

Damage to hay production is minimal. Insects are 7mm long and half as wide, are broad, flattened and oval shaped with small projecting head. They range in color from yellowish-green to reddish-brown. Distinguishing mark is a yellowish triangular area between the wing bases.

 

 

 

Click on the link below for help with minor insect problems.

 

Bob O'Donnell - America's Alfalfa