The Boring Sod Webworm


It is another great week at the Wonderful World of Weed Man!  I am happy you could join us.  Last week we discussed the Cranberry Girdler.  Up to this point, we hope you have enjoyed the, “I Found An Alien In My Lawn!” series.  We will be finishing out the series today with information regarding the Sod Web-worm.

This lawn insect just is not very exciting.  Many times it goes unnoticed.  It doesn’t have a cool or catchy name.  It doesn’t come from an exotic land.  It lacks superpowers!  It is just the boring Sod Web-worm.

The Sod Web-worm is sometimes known as the ‘lawn moth’.  As an adult you are more likely to realize they are around as they are a dull brown/grey colored moth with a long snout extending from the head.  Generally, the adult moth will not do any damage to your lawn.  However, the larvae, that hatch from the eggs they lay will do significant damage to your lawn.

The web-worm will generally have 2 generations each year.  The 2nd generation will overwinter as a larva until April the next year.  They survive the winter in the soil and thatch in a silken tunnel.   It will transform into an adult moth around mid-May or June.  They will then hang out in the grass during the day.  In the evening they will flit back and forth across the lawn laying eggs.  The eggs will hatch in 1-2 weeks and the new generation will start the process over again.

Sod_Webworm2202The larvae, as mentioned earlier, will damage the lawn by feasting on grass leaves and stems near the soil surface.  They do this at night, and will hide during the day within a silk, webbed, burrow in the thatch layer.  Thus the name ‘web-worm’.  They do like most types of grasses, including common grasses in our area:  Kentucky Bluegrass, Bent grass, and tall/fine Fescues.  Although the web-worm is active from spring to fall, most of the significant lawn damage occurs in mid to late summer.

The damage from the web-worms will show as a brown spot the size of a baseball.  The grass stems and leaves will have been chewed upon just above the crown.  Homeowners often mistake damage from sod web-worm with dog spots.  However, the web-worm damage will not turn yellow before turning brown like a dog spot would.

The University of Nebraska-Lincoln’s Institute of Agriculture and Natural Resources Department of Entomology has some great advice on how to investigate your lawn to see if you have sod web-worm.  “An early sign of potential infestation is sod web-worm moths zig-zagging over the turf at dusk. If a sod web-worm infestation is suspected, closely examine the turf for evidence of insect activity. Small patches of grass will be chewed off at ground level. Fresh clippings and green fecal pellets are also usually present. Examine the thatch layer and top inch of soil for larvae, silken tubes and webbing.”

There is also an easy way to visibly see the sod web-worm if you think you have them.  A solution can be made from 2 gallons of water and 2 tablespoons of liquid dish soap.  Pour the solution of the suspect area.  The larvae are irritated by the solution and they will come to the surface of the lawn.

Once you have discovered your web-worms, what do you do about them?  Here are some good options on resolving this lawn pest:

Natural Predators – Birds eat web-worms!  They can actually reduce the population severely by the time fall rolls around.  Nevertheless, birds dive-bombing your lawn may not be the best option for a quick or clean solution.

Biological Control – Insect Parasitic Nematodes will combat web-worms, much like other lawn eating insects.  This can be applied via a liquid spray – however it is important to pay attention to application instructions.  Nematodes need a very specific environment to be effective.  Temperatures too high or too low can influence how effective their performance will be.  Water levels in soils are important to be aware of too.

Insecticidal Soap – This is a very temporary natural insecticide.  It will irritate and remove the outer layer of the web-worms body, causing it to dehydrate severely and die.  You may have to use several treatments of this or buy a large quantity depending on the area you need to treat.

Chemical Control –  Most insecticides are safe when applied CORRECTLY.  If you are not sure about how to use insecticides safely, please contact a professional for assistance.

There has been a lot of concern about safety when it comes to insecticides.  We take safety very seriously when applying treatments on the lawn.  Weed Man uses only products for use on home lawns. They are most safely applied in the capable hands of a trained professional like Weed Man.  If you have an issue with Sod Web-worms, and would like help, please give us a call! 208-888-9911 #wecareforyourlawn







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