Armyworm

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Armyworms

Knoxville, TN Armyworms are a turf damaging insect pest found generally east of the Rocky Mountains, but can be found throughout North America. In North America there are a few different types of Armyworms: the Common Armyworm, Fall Armyworm and Yellowstriped Armyworm. The larvae feed on all types of turf and can damage ornamentals, vegetables, as well as forage crops and cereals. Armyworms are thought to be semi-tropical in origin likely from Mexico or Central America and now have taken up permanent residency in and along the Gulf States. Adult Armyworms resemble moths and will migrate north and westward during the spring and summer. Large infestations have occurred further north after large populations of adults have been blown north due to tropical storms. Turf that is damaged by armyworms will appear dry and wilted as stems of plants are completely consumed.


Knoxville, TN Armyworm Larvae

Damage

Armyworms feed on  grass anytime during the day and are known for their voracious eating habits. They have been seen moving in masses from one turf grass area to the next eating everything that is green, leaving behind only a few stems. Normally the damage appears as drought damage with a wilting yellowing appearance. Starlings can sometimes be an indicator of the presence of a significant Armyworm population as they like to scavenge the lawn looking for the larva to feed on. Armyworms can turn a healthy, lush green lawn brown and dead looking overnight. Large portions of your lawn will be gone the next day.

Life Cycle

The Armyworm overwinters in the larva or pupa stage in the southern regions of the United States.  In the northern regions of the United States, some larva may overwinter but most adults are blown north with spring weather fronts. In the spring, the larvae pupate and or the adults that arrive will mate and the females will lay clusters of eggs consisting of 100-300 eggs left usually on grass tips, hanging trees and shrubs or structures. Females can lay 1000's of eggs. The eggs will hatch into larvae and feed on the grass until they devour the entire plant;  Then, they will spread out feeding on the grass at anytime during the day. Over a period of 20-48 days, depending on the temperature, they will go through 6-9 instars before pupating in the thatch and soil. Depending on the location, there can be several generations present; Usually 2 generations in the north and up to 6 generations in the south.

Management

Control of Armyworms is typically accomplished through post insect control, once an infestation is noticed. Two rounds of insect control are needed in order to control the active Armyworms and another round is needed to hit the remaining Armyworms that are in egg form and hatch later.  Timing of the two applications is very important and recommended in order to ensure the most complete control of the insect.  The benefit of each application will last for up to 20 days. Please note, in one single night of feeding, the Armyworm can destroy a lawn.
 
Proper fertilization is extremely important and Weed Man's exclusive brand of granular slow release fertilizer ensures that the turf remains healthy all year long. It is important to maintain Adequate nitrogen levels for the health of your lawn and will help the turf plant recover more quickly if it is thinned out due to Armyworm activity. Proper watering is also a key factor in the management of Armyworms; therefore, it is important to follow Weed Man's proper watering instructions to help prevent Armyworms on your turf! Further, homeowners should ensure their lawn is cut with a sharp mower blade when the grass is dry and at the recommended mowing height for your turf species

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