It’s that time of the season when these little, seemingly harmless moths, show up throughout the region and wreak havoc on the area’s lawns. These little moths, left unchecked, can cause a lot of damage. Starting in June and continuing sometimes until October, sod webworm larvae feed on the grass in your lawn. Now under “normal” conditions there is usually little evidence of their presence or damage, because they do not damage the root structures.

Most of their damage fixes itself with regular rainfall and/or homeowner watering, but during drought conditions, or in cases of extreme infestation, their damage is more extensive because the damaged turf does not receive adequate rainfall to replenish damaged grass.

sod webworm larvae
sod webworm larva

So that begs the question, “How do I know if I have them?” The main telltale sign that they are present is when little brown moths can be seen flying out of the lawn whenever the grass is disturbed. The good news is that the adult moths do not feed on the turf. The bad news is that these now adult moths have been already feeding and their newly laid larvae soon will be. Another sign to look for is any type of gathering of birds in your lawn. Birds will feed on the young larvae, so any noticeable gathering in your lawn could be a sign that something is amiss. Lastly, damaged areas will primarily be located in the sunniest exposures of your lawn. So, any browning in those type of areas should be inspected by your lawncare provider immediately.

sod webworm moth
sod webworm mot

As for treatment, a topical insecticide needs to be applied. (If you are one of our clients, and you received this flyer, then your lawn has already been treated as needed. See your invoice for any further instructions). Ideally, the insecticide should be allowed to sit, without being watered in, overnight because the larvae are nocturnal feeders. After that, begin a regular watering program that will help these damaged areas recover.

Common Questions:

I had a grub preventative so why do I have these insects?

Simply stated, there are no preventatives for sod webworm, or any other surface-feeding insects. Because sod webworms are surface feeding insects, they can only be controlled when they are present. (Unlike grubs, which are sub-surface feeders, where a barrier can be put in place prior to their feeding.)

If they are treated once will that take care of the problem?

Maybe, but as stated above there can be as many as 3 or 4 cycles of sod webworm activity depending on the weather conditions. While we treat them whenever we see them, at no additional cost to you, we are only out on your property 4-5 times a year. Therefore it is up to you, the homeowner, to monitor your lawn and let us know of any concerns that may arise.

Will the damaged areas recover?

In most cases, yes. Depending on the severity of the damage and how long it when untreated, most damaged grass will repair itself. But regular watering is the key for complete recovery. Please be sure to follow the suggested guidelines for watering.

As always, if you have any questions, please call the office at 815-469-5566



“What is it and why am I seeing it in my lawn?”

Please note that our area has been hit by drought conditions spanning from the end of June up through the end of July. Consequently, with this drought has come an increase in crabgrass growth.

Batch of Problematic Common Crabgrass
Batch of Common Crabgrass

A common question we get is, “If I had the pre-emergent applied in the spring, why do I have crabgrass at all?” The answer is that pre-emergents are simply chemical barriers located beneath the soil. That barrier will remain intact as long as the soil is not disturbed. When we experience these drought conditions (less than 1 ½ of rainfall from June 24—July 22), the soil begins to crack from the lack of moisture. When the soil cracks, the barrier also cracks with it. Short of keeping soil properly irrigated, there is simply no other way to prevent this from happening. Couple that with the facts that bluegrass starts to go dormant during hot, dry spells and crabgrass thrives in these conditions, your lawn can see an invasion of crabgrass growth very quickly. You may also see crabgrass along curbs, sidewalks, and any areas that are edged because this also breaks up the barrier in the soil.

“So what is being done about it?” Rest assured that if you have any crabgrass, our technician treated it today. Allow 10-14 days for complete control. We will continue to monitor your property for any further potential activity in the weeks to come.

But as always, if you see anything that is not right, or if you have any further questions, please call 815-469-5566.