Cutworms are a pest that have began to show up more and more in the Willamette Valley over the past few years, mainly with the emergence of the Winter Cutworm that we see this time of year. Cutworms are the larvae (caterpillars) of moths that we typically see flying at night around that light above the barn door. There are many types of cutworms but all have some common identification points and characteristics. All cutworms have 3 pairs of true legs which are located toward the front of the body. They also have 5 pairs of pro legs, 4 pairs in the middle of the body and 1 pair toward the rear. The difference in cutworms comes in the color and markings of their bodies. Cutworms can usually be found in fields under debris such as leaves, sod clumps, or soil clods, and can be found more commonly at night while they feed.
Below is a picture of a clover cutworm commonly identified by its lime green color and a series of 5 stripes running down its body.
In this next picture you can see the same cutworm curled up in the "C" position which is how you commonly find them after being disturbed. It also shows the pro legs located on the underside of the body.
You may have seen cutworm damage in your field before and wondered how they "cut" the leaf surface so clean to make it look as if the area had been mowed off. That is because of the cutworms aggressive feeding habits and its exceptional mouth parts that allow it to cut clean through a leaf. If you find a larger area of damage, that happened very rapidly sometimes over night, it could be from army worms which are a type of cutworm. The army worm gets its name from moving in mass numbers, like an army, and feeding in a line across the field.
Below is a short time lapse video taken in our office to show you how quickly these pests can feed on a crop. This is a wheat plant that is just getting its second leaf out and as you will see it wont last long. This time lapse was taken over 6 minutes and 15 seconds and compressed into a shorter version.
Hopefully this information gives you a little better understanding of cutworms and the problems that they can cause. The key to staying on top of the problem is continuously scout and monitor for damage. If you have any questions please contact your field man, and as always thanks for visiting our page!