Their population explodes in Pa.

Army worms are not new to Pennsylvania, but this year’s population has exploded and there are reports of damage to crops across Pennsylvania.

An insect that feeds primarily on plants in the grass family, army worms can cause significant damage to hay crops, grain fields and even lawns near agricultural fields. Under hunger stress, the army worm also may attack some legumes and other plants.

These caterpillars are named for their tendency to move en masse to their next source of food. They will cross roads or other obstacles in their path to satisfy their hunger.

The caterpillar stage of this insect lasts about three weeks, but caterpillars are usually 10 to 14 days old before damage is noticed. Larvae that reach maturity pupate in the soil and the next generation moths emerge 15 to 18 days later. Multiple generations of the insect are seen during the course of the summer.

According to John Tooker, assistant professor of entomology in Penn State’s College of Agricultural Sciences, the insects feed at night and the damage will vary depending on the plant.

In corn, they take large chunks out of the leaves. In wheat, leaves are eaten but the most noticeable damage is clipping of wheat heads. In grass or hay fields, the army worms consume the leaves and seed heads, leaving the round stems of the plant. Lawns adjacent to grain fields also may be overrun by army worms as they look for new food sources.

While there are insecticides labeled for the control of army worm, control can be difficult if caterpillars are greater than one inch in length. A list of recommended insecticides for grain crops can be found in the Penn State Agronomy Guide, found on line at http://extension.psu.edu/agronomy-guide. The pest management section contains additional information on management of army worm and other pests.

The Pennsylvania Department of Agriculture reminds producers of the following process to report crop damage:

To file a crop insurance claim:

• Call your crop insurance agent within 72 hours of discovery of damage, and follow up in writing.

• Do not destroy evidence that is needed to support your claim without clear direction from the insurance company’s adjuster in writing.

Whenever there is damage due to insects and/or disease, it is critical to do the following:

• Substantiate that it is uncontrollable.

• Show preventative measures that were taken — making sure you are following good farming recommended practices.

• Show measures that you have taken and the timing of the action taken since you determined there was damage.

Producers should contact their local crop insurance agent and the local Farm Service Agency office immediately to report crop damage.

This material is submitted by Donna Zang, extension director, and the staff of the Penn State Extension office at the Sunnyview Nursing and Rehabilitation Center complex.