Native Plants

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Thursday - August 21, 2008

From: Sugar Land, TX
Region: Southwest
Topic: Pests
Title: Webs on trees and porch
Answered by: Nan Hampton

QUESTION:

i have webs all over my semi covered porch in my back yard. i have noticed these small webs are also on the trees in my backyard. what are they and are they dangerous to the trees or my family who sit on our back porch.

ANSWER:

We aren't entomologists but we'll tell you what we know about webs around the Central Texas area. There are webworms (Hyphantria cunea) and there are tent caterpillars (Malacosoma americanum) that build webs in various species of trees. The webs enclose moth caterpillars that feed on the leaves. One of these might be a possibility for the webs in your trees, but aren't very likely to be what is on your house since there is no food there for the caterpillars. As for harm, they can damage your trees but don't pose a danger to you, your children or your pets.

Another possibility for webs on trees, generally on the trunk of the tree, are barklice (Archipsocus nomas). The bark lice, which aren't really lice at all but insects called psocids, are feeding on fungi, lichens and other debris on the trunk of the tree. In other words, they are cleaning your tree and, thus, are probably beneficial to it. They produce the web to protect themselves from wind, rain and predators. Since they feed on fungi, algae, lichen and such, it is possible that they could be feeding on these organisms that grow on your covered porch as well. The bark lice, like the caterpillars, are not harmful to you or your family, nor are they harmful to your trees and/or porch. Here are photos of bark lice.

I suggest that you contact the Fort Bend County Extension Service. They may have some insight about what is building webs in your area.