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Beet Armyworm

Scientific name – Spodoptera exigua

Beet armyworms get their name from the unique habit of moving in large numbers from field to field when overcrowded or when the food supply is exhausted. Newly hatched beet armyworm larvae are light green. When fully grown, they range from light green to almost black. They have a dark spot on each side of the thorax just above the middle pair of legs. Full grown larvae are 1ΒΌ in length. Two generations are produced each year in the north central United States and three to four generations occur in the western growing areas. 

Symptoms 
The larvae damage sugarbeets by feeding at night, and are capable of destroying and consuming large amounts of foliage in a short amount of time. First generation larvae usually do most of the damage by feeding on small seedlings although later generations may appear in July and August and cause significant defoliation.

Control 
Timely application of insecticides is the best method of controlling beet armyworms. Managing early weeds to reduce the attractiveness of egg laying activity is helpful in keeping populations of the pest in check.