Sod Web Worm

The sod web worm can cause great damage to grass and crops such as corn, oats, and wheat. They are especially destructive to grassy areas such as cemeteries, golf courses, and the lush landscape in most parks. The sod web worm does the most damage to crops and grass in its larval stage. Once the web worm transforms into an adult moth, it no longer has a taste for grass or crops of any kind. The moth isn’t interested in consuming clothing either.

If your lawn, landscape, or crops are infested with sod web worms, you will notice damage around early spring. You can tell which areas have been damaged by the dusty, brown patches dotting the area or landscape. The brown, patchy grass is an eyesore when placed alongside normal grass or crops. The worms may feast until a month or so before fall or early august. While sod web worms will feast on just about any bed of grass or field of crops, they frequent sunny areas on south facing banks and steep slopes. These areas are hot and dry – just how the sod worm likes it. It is not uncommon for sod web worms to attack shaded areas, but when faced with a decision to destroy a sunny area or a shaded, the sunny area will win every time.

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Besides dry, brown patches, to detect sow web worm activity, look for thinning areas throughout the grass or turf. A closer look will reveal little green pellets or “frass,” which is the sod web worms feces. You can also look for sod web worm adults. They are beige colored and ¾ inches long with a elongated cigar-like shape. When at rest on a grass blade, the sod web worm adult wraps its wings around the body. You will notice two small projections at the front of the moth’s head.

Sod web worm larvae are typically less than one inch in length and they have dark spots all over the body. Some may have light spots as well. Just a few of the different types of sod web worms include:

  • Bluegrass sod webworm, Parapediasia teterrella (Zincken)
  • The cranberry girdler, Chrysoteuchia topiaria (Zeller)
  • The larger sod webworm, Pediasia trisecta (Walker)
  • The striped sod webworm, Fissicrambus mutabilis (Clemens)

The vagabond sod webworm, Agriphila vulgivagella (Clemens)

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There are many ways to control sod web worms. You can use cultural controls such as a mixture of fertilizer and water, biological controls such as natural parasites of Bacilus thuringiensis (BT), resistant turf grass varieties, or chemical controls (sprays).

A combination of fertilizer and water will allow the damage to outgrow. Biological controls such as natural parasites (beetles) will control even large sod worm populations, if you do not use insecticides. BT (bacterium) can be successful in the early stages of sod web worm development, but may not be effective when the worms are too big and perennial ryegrasses and tall fescues *(resistant turfgrass varieties) contain fungal endophytes that are resistant to web worm attacks. Chemical controls such as contact or stomach pesticides should be used in the form of a spray. The spray should be administered in the late afternoon hours.

Please note that if you decide to use any chemical controls, you should use them according to the instructions and the laws in your state.

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