Capture of armyworm moths in the IPM pheromone-baited traps at the UK-REC (Princeton, KY) site has increased substantially.

The number of captured moths for the week ending 18 April 08 was well in excess of 300 moths / trap week. These counts are on a par with the 2006 “outbreak year” numbers and are well above the rolling five year average. You may see a graphic display of these results by going the IPM web pages. Look at the bottom of the page and “click” on “True Armyworm”.

Capture numbers for the Spindletop Farm (Lexington, KY) have not increased as rapidly. On the other hand, the Spindletop location is always a bit behind the Princeton location because of temperature differences.

Remember, these are captures of moths (adults) which are not the damaging stage. It will be a week to several weeks before the caterpillars (damaging stage) begin to appear, depending upon temperature. Nevertheless, this should serve as an alert that: 1.) the numbers are greater than usual, and 2.) the insect is active.

Producers, consultants, Ag-Extension Agents, and Ag-Business should be aware of the possibility of damage from these insects. Continue to watch the trap counts and check the Kentucky Pest News for further developments. I will be using a temperature driven model to predict the appearance of the caterpillars.

Armyworms are predominantly “grass loving” insects. They will feed on broad leaf plants including soybean, but damage to broad leaf agricultural crops in Kentucky is very rare. Be especially watchful on grass for hay / pasture and small grains.

The caterpillars populations will appear in small numbers, reach a peak population, then begin to decline. Caterpillars are greenish brown, with a narrow strip down the middle of the back, and two orange stripes along each side. The head is yellowish with honeycombed dark lines. A newly emerged caterpillar will be quite tiny but may reach a size of 1-1/2” in length. Caterpillars (that don’t get eaten or parasitized!) could be expected to live on average about 18 days at 80 deg F to 26 days at 70 deg. F.

The following is based on the Princeton Site:
At present, with the temperature data available, caterpillars from the moths flying between 12 Apr and 18 Apr 2008 should be appearing about 04 to 06 May. Of course not all the caterpillars will appear at the same time. Remember there were some moths flying before these dates.

Leave a Comment

Name (required)

Email (will not be published) (required)

Website