Eggs hatch in 2 to 3 days. The newly emerged larvae spin loose webs around themselves, feed gregariously on the remains of the egg mass, and then attack plant foliage. They eventually scatter to different parts of the plant. About 1 week later moths emerge. The entire life cycle requires 4 to 5 weeks.
Several generations occur each year.
The beet armyworm has few effective parasites, diseases, or predators to lower its population and is resistant to some insecticides. Therefore selection of the proper material and rate is very important when chemical control is considered. When defoliation reaches the economic threshold of 35 percent foliage loss before bloom or 15 percent foliage loss after bloom, consult the current North Carolina Agricultural Chemical Manual .