At the beginning of this month, I started getting lots of turf calls about caterpillars. We are still seeing them rampant now. They are sod webworms and different species of armyworms. I have mostly seen sod webworms, which are less than an inch long and have dark spots over their body. They overwinter as caterpillars in protective webbing. In the spring, they feed and molt into the pupal stae. The adults emerge, fly and mate. They have two or three generations a year.
It is recommended to treat in the young larval stage; however, its later instars that do damage to the turf. It’s easy to see the chewed grass blades. Sod webworms tend to survive better in higher-cut turf. This season, I’ve noticed them in St. Augustinegrass. I have seen them previously in centipedegrass.
We have been discussing treatment and checking behind turf that has been sprayed. You won’t find the dead worms because the organic matter is very high, unlike row crops, where dead bodies are quickly broken down by microbes and fungus is thatch. UGA Extension Enotmologist Dr. Will Hudson says they have developed an adaptation where if they are sprayed in the latest larval instar, they will go ahead and pupate. In South Georgia, caterpillars can be in issue through the month of September.
What about adult moths? We are still seeing a high amount of moths. It is not recommended to treat moths since most moths do not produce caterpillars that survive to a size that will do noticeable damage. Dr. Hudson says – as of now- it’s pretty late in the season for another generation to do much damage to a healthy lawn.
Another pest I just saw this week is damage from chinch bugs. Chinch bugs infest during dry conditions. Our rain in Thomas County has been very spotty the last 3 weeks. We’ve been over a week in town without rain, and I saw this damage at our courthouse. There was no chewing on the grass blades, so I looked in the grass and found chinch bugs.
Chinch bugs have the piercing/sucking mouthparts like stinkbugs and feed at the base of the grass blade. This damage shows up as discoloring of the leaves and stolons. They tend to associate with St. Augustinegrass. They feed in clusters and damage first appearch as circular patches of yellowing turf that resemble drought. They are very tiny – can fit inside your pinky finger nail. Pull back the grass and look through the thatch. If they are present, you will see the bugs crawling around. They are so small, it is difficult to catch them.
Here is one I caught and put on the microscope. I could tell he did not have wings and is immature. They have a gradual metamorphosis where immature resemble mature except without wings. The only difference is color. I sent this to Dr. Hudson and he said this is second instar. The first instar is bright red, then this color for the next. Then they turn gray for a couple of molts, then get darker for the last stages. I was asking him about white color ones I was seeing but couldn’t catch. “The whitish looking ones are probably adults, since the wings are reflective and give a white appearance.”