As summer begins to wind down, fall armyworms and bermudagrass stem maggots are multiplying in Georgia.
While it is obvious by the name as to what bermudagrass stem maggots feed on, fall armyworms will eat most any forage plants or turfgrass.
Both of these pests can cause severe yield losses to bermudagrass hayfields and need to be scouted for early to effectively control the damage.
The lifecycle of fall armyworms usually starts in Florida with the adult moths migrating north and laying masses of eggs that eventually develop into caterpillars and cause serious damage to lawns and forage grasses.
Fall armyworms grow into caterpillars with a light green or black coloring that includes dark stripes and an inverted Y shape on their heads. Once mature, they will develop into moths and restart the reproducing process.
These pests typically feed in the morning and evening and will result in damage that looks like thin brown patches of grass.
One way to check for fall armyworms is to add two tablespoons of lemon-scented soap with a gallon of water and pour it onto one square foot of the grass. If more than three armyworms per square foot appear, control measures are necessary.
For controlling fall armyworms, insecticide application is the very effective. Sevin dust, Spinosad or Bacillus thuringiensis are all good options. The best time to apply these insecticides are late in the evening. Always be sure to follow the label directions carefully.
If you notice your pasture looks like it has just been through a frost during the summer, then bermudagrass stem maggots are probably the culprit.
These pests will start their life cycle on a bermudagrass leaf and the larva will hatch and eat through the stem.
The damage from these pests depends on the maturity of the plant being fed on. If the bermudagrass is immature, the yield loss can be catastrophic, whereas if the grass in close to harvest time there may only be a 10 percent lower yield.
While timely harvests of bermudagrass hay are a good way to lower the yield loss from these pests, insecticide applications seven to ten days after harvest can significantly reduce the damage. A second application a week after the first is also recommended if the infestation is severe.
Insecticides recommended for bermudagrass stem maggots include many pyrethroids such as Bifenthrin, Cyfluthrin and Lamba-cyhalothrin.
For more information on these pests, check out these UGA Extension publications on bermudagrass stem maggots and fall armyworms.
For help identifying a pest, contact your local Extension agent or bring a sample to the Extension office for identification.
