August 21, 2014

Gardening: Funnel Web Weavers keep insects in check

Q. I have noticed a large number of small spider webs scattered around my lawn area, perhaps a hundred or more. What are these and are they harmful? What should I do about them?

-- D. L. of Caseyville

A. You are describing the Funnel Web Weaver spider or Grass Spider (Agelenopsis species). I cannot get this spider down to the exact species because there are more than 400 species in North America and only a specalist can identify them. If you are interested in identifying this genus of spiders, you have to examine the head as they can have four to eight eyes with different arrangements on the head. Not too many people are interested enough in spiders to examine them this closely.

Their webs are present through most of the summer but really show up during the later part when dew forms on the web in the early morning. If you look closely, you will see a funnel formed in the web, hence the common name. These spiders are very fast. The webbing has a three-dimensional barrier web at the top. When a flying insect hits this barrier, the insect falls to the bottom web or sheet and the 3/4-inch-long spider rushes out of the funnel, bites it, and drags it back into the funnel. The bottom sheet webbing is made of non-adhesive silk.

At this time of summer, it's easy to see where they are. They do an excellent job of keeping the insect populations down. A folklore saying states: When you see the dew webbing in the morning, a beautiful day will follow."

Q. I have a circle of white mushrooms that appeared overnight in my lawn area. What are they and how do I get rid of them?

-- D. V. of Belleville

A. First, let me tell you about your lawn. You probably have the best looking lawn on the block, with very few weeds. You fertilize it on a timely schedule as well. These mushrooms are your badge of honor for doing such a great job. So pat yourself on the back for a great looking lawn.

The mushroom responsible for the fairy ring is Amanita thiersii. This mushroom migrated by spores from Texas to our area in the 1990s. Dr. Walter Sundberg of Southern Illinois University-Carbondale discovered and identified this species around the summer of 1992. I was one of his students during the summer semester.

This mushroom is easily controlled by mowing it, which destroys its fragile tissue. Or you can hit it with a strong stream of water, which will do the same. It is not edible as it has a strong odor of urine. This mushroom was first described in the book "Mushrooms Demystified" by David Arora in 1979.

Each year the fairy ring will grow larger in this same area and may spread spores that develop in other areas of your lawn. If you want to stop them from producing these fruiting bodies, inject water with a tree watering probe and flood the area. That will cause the fruiting bodies to burst from taking in so much water.

Do it now

CLEANUP: When cutting dead tops off plants, be careful not to put diseased foliage on the compost pile.

HOUSEPLANTS: Begin to think about bringing in the houseplants as the evening temperatures this year may be cooler a little earlier.

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