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Here is an interesting lawn problem that is quite rare, but seems to come up almost every spring here in Iowa.  People will call and say that they appear to have cigarette papers all over their lawn.  They usually do not see an insect associated with the problem and the question is, “what could possibly cause this?”   

The problem is caused by an insect called the Burrowing Webworm.  It is in the genus Acrolophus.  Other common names include Cigarette paper webworm or tube moth.  There are reportedly 65 species within the genus.  Like the more common Sod Webworm, the larvae live in a web-lined burrow just under the surface of the lawn.  In the case of the Burrowing webworm, birds feeding on the larvae pull out the webbing, consume the larvae and leave the cigarette paper-like webbing on the surface.  It is not usual to see hundreds of these on the lawn after birds have been there.  They disappear very quickly with moisture and the larvae are generally not seen because the birds ate them. 

While the larvae can feed on turf, they rarely do any serious damage to lawns.  Most common insecticides for surface feeders will kill them.  However, most of them are generally gone because of bird feeding when the paper-like burrow is observed and insecticides would not be recommended. 

I would like some more pictures of the papers.  If any one sees them, send the pictures to Nick Christians at  nchris@iastate.edu.

Picture of Cigarette paper-like burrow lining.  Courtesy of Laura Iles of the Plant and Insect Diagnosis Clinic at Iowa State University.

Picture of adult Burrowing Webworm from the web.  It is from New Hampshire Public Television. 

I received the following pictures from Gary McVay.  They are from St. Charles Ia, south of Des Moines.  They were taken the week of June 19, 2017.

In this picture the hole from which the larvae and paper were taken by birds is visible.

Here are a couple more from the Boone, Ia area from 6/23/17.

Here are two new ones from the Ames area, 6/27/17

Here are a few more from 6/27/17.  These are from Ida County.

Yet another one from the North side of Ames on 7/5/17

Rough bluegrass, or Rough Stalk bluegrass, Poa trivialis is closely related to Kentucky bluegrass (Poa pratensis).  There are some important differences, however.  Rough bluegrass is common in Iowa lawns.  It is a source of many calls at this time of year, because it tends to turn brown more quickly than the Kentucky bluegrass in times of heat and drought.

It forms patches of a light green, dense turf in the spring and fall when there is enough moisture.  It is best adapted to wet shaded conditions and may be included in seed mixtures for that environment.  Unfortunately, it often grows out into full sun areas.    It is very intolerant of heat and drought and turns brown in dry summers.   It is not dead, but dormant and will recover quickly when it cools down and there is more moisture.

Kentucky bluegrass has underground stems called rhizomes, whereas Rough bluegrass has stolons.  It has a boat shaped leaf tip and a folded vernation like the Kentucky. 

It is often mistaken for a disease problem in Kentucky bluegrass.  One needs to look at it closely to see the stolons.

Slide shows stolons (above ground stems) of Rough bluegrass.  Picture from American Society of Agronomy (ASA) turf slide set.

It has a boat shaped leaf tip and folded vernation, like Kentucky bluegrass.  It's membranous ligule varies from short to quite pronounced.  In this picture, the ligule is short.

It sheath is like the middle picture, split part of the way down, whereas Kentucky bluegrass is split all the way to the node.  (ASA slide set)

Lower sheaths may take on an onion-skin like appearance.  (ASA slide set)

In spring it appears as light green patches in the turf.  (Taken from web, source Dr. Zac Reicher)

In hot dry weather it may turn reddish or a light purple color and then turns brown.

There is no selective control for it in Kentucky bluegrass.  You either need to live with the brown spots in summer, or wait until it recovers, kill it with glyphosate (Roundup) and seed back into the dead spots with Kentucky bluegrass.  Roundup will not kill it when it is dormant.  Sufficient irrigation in midsummer may also prevent it from going dormant.