The Importance of Proper Identification
Proper identification is the first step in any control program. If you learn nothing else about pest control, at least remember that. An incorrect identification might lead to treating for something that isn’t the problem, and your control program will be ineffective. This is one of the main reasons why do-it-yourself pest control efforts fail. Fire ants, for example, are not receptive to bait meant for other ants. Fruit flies, fungus gnats, and phorid flies are all small “gnats” but they breed in different places and signify different problems. If you’re treating the drains for fruit flies but actually have fungus gnats, you really needed to turn your attention to the overwatered houseplants.
I received a phone call along with these smart phone photographs asking about how to control spiders making webs in the lawn.
Photo credit: Mark Sumner, Auburn Pest Supervisor
Remember what I said earlier? Step one is identification. The assumption was made that these were spiders because webs are associated with spiders. That may be mostly true, but it is not always true. Caterpillars spin silk and some make webs, like the eastern tent caterpillar, which you’ve undoubtedly seen but may not have known what it was. Some species of mites, like the two-spotted spider mite, create webs over houseplants and food crops. There are countless other examples.
The webs in the first two lawn photographs were not constructed by spiders. They were not the product of caterpillars or mites, either. In fact, those webs weren’t made by insects or arachnids at all – they were formed by a fungus called dollar spot. The silky appearance is not silk at all; it is mycelium, the branching, thread-like, growing portion of a fungus.
What if we had treated for spiders? We would have wasted product, labor, and the customer’s time and money. As we treated the imaginary problem, the real problem would have worsened. The customer would have gotten frustrated and lost confidence in our company, and we would have been frustrated, too, because we were doing everything we could to solve their problem. This is why we take the time to identify.
Some spiders do make their webs in the grass. Grass spiders are a thing and they do exist. A key difference is that grass spiders have a cone- or funnel-shaped portion in their web where they hide and wait for prey. To be certain, you can disassemble webs and find the spiders (use caution, because spiders can bite when disturbed). Of course, not all spiders that make webs in the grass are grass spiders, but they are the most common one you’ll encounter.
Grass spider web. Photo credit: Tony Atkin, CC BY-SA 2.0.
Grass spider making an appearance. Photo credit: Dr. Gordon E. Robertson, CC BY-SA 3.0.
The webs made by dollar spot tend to disappear after the morning dew dries out, while spider webs are visible any time of day. Eventually, with dollar spot, your lawn will get brown patches that start out about the size of a dollar coin. These patches get larger over time and look like drought-stress. Watering tends to make the patches worse, because fungi love moisture.
Dollar spot symptoms on creeping bentgrass. Photo credit: Glenobear, public domain.
As with most fungi, dollar spot spores are everywhere, all the time, in every lawn, in every neighborhood. It only becomes an issue when certain conditions arise (overwatering, insufficient nitrogen, poor aeration, etc.). I am not a lawn specialist so I won’t go into how to solve a dollar spot issue. That is in the realm of other experts.
The point of all this is be sure you know what you’re dealing with before you throw time, money, and products at a problem. To the untrained eye, dollar spot looks a lot like spider activity. You may want to enlist the help of an expert before you become frustrated with trying to solve a problem on your own. In the case of dollar spot, a lawn expert could help you identify and solve the lawn issues causing your dollar spot problems.