Scouting for fall armyworms

Armyworms are one of the most destructive pests there is to forage, and specifically Bermuda grass.

Whether it is pastures, golf courses, or lawns, they can rapidly consume a great amount of forage.

For hay producers, it is extremely important to prevent armyworm destruction given the current shortage of hay and increased prices.

As such it is important to scout for, and control, armyworms before infestations get out of hand. Armyworms, with the marching nature which they are named for, can destroy fields overnight, due to their immense appetite and rapid multiplication.

Armyworms tend to have a significant uptick following large rain events. While they are present throughout the year, rain conditions allow more eggs to survive, which can quickly multiply their numbers.

They prefer moisture and cooler temperatures, which has led to their increase in numbers recently. They can lay up to 2,000 eggs that rapidly hatch, which gives them the capacity to destroy pastures in a very short period. Fertilized pastures are especially susceptible due to their preference for dense growth to feed on, putting hay producers at high risk.

The first step in controlling fall armyworms is knowing they are there. To do so, it is important to regularly scout fields and pastures, especially after rain events.

Armyworms can range in size from 1/8 inch to 1-1/2 inches long, depending on their stage in the life cycle. They are predominantly green in color with brown or black stripes running down their body, and white markings on their head. Because of their small size, it is often necessary to closely inspect pastures to tell their presence.

The best time to scout is in the morning, as this is when they will show more activity. Generally, if there are 2 or more fall armyworms per square foot, it is time to treat.

The primary method of armyworm control is through insecticides labeled for their control in pastures. The most economical of these is pyrethroids. These can quickly be effective on armyworms; however, they have very little residual effect, meaning it may take multiple sprays to fully control the population.