EARLY ARRIVAL OF INSECT PESTS

The recent strong southerly winds we had for what seemed like forever brought with them some unwanted visitors.  A few insect pests have arrived in the state early, from one to several weeks earlier than normal.  Following are a couple to watch for: 

1. True Armyworms.  These relatively rare pests have arrived in the southeastern part of the state, and in economically important numbers.  Watch wheat, barley and oat fields carefully, as when these pests arrive, they are truly a problem that demands immediate attention - they can be a true “army.” The moths of these larvae are relatively non-descript, but the larvae of the true armyworm is the problem. They are fairly easy to identify simply by looking at the HEAD. If it is orange and has black fine lines, it is probably a true armyworm.  Other larvae around now usually have a solid-colored head.  Insecticides are effective, but watch PHI limitations as we near winter wheat harvest. Read article from SDSU here.
2. Alfalfa webworms. The damage caused by Alfalfa webworms looks similar to damage that can be from thistle caterpillars but the insects appear different. The Alfalfa webworm has a  dark head capsule and few spines as compared to thistle caterpillars. They loosely spin webs holding a couple leaves together and can defoliate young soybeans.  SDSU has also been hearing of issues with them in sunflowers this year too. The threshold for treatment is high, however, and will be at an average of 20% defoliation for spraying, just like thistle caterpillars or grasshoppers.  Insecticides are effective, if coverage is good.   
3. Other insects: Keep an eye on alfalfa weevils which are still active and abundant.  Start looking for leafhoppers and thistle catperpillars should be arriving soon, too.  Soybean aphids should not be far off, if they are going to appear.