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June 19, 2017

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


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




July 13, 2017

For the Blog from Dr. Donald Lewis

The annual cicadas have been buzzing in the trees for the past week, and right on schedule, and right behind them, come the cicada killer wasps. 

Cicada killer wasps are 2-inches long with black and yellow marking and orange wings.  Their size makes them look and scary but they are not a threat to people and pets.  But still people want to kill them because of their size.

Cicada killers are a solitary wasp. There is no colony as there is with honey bees, bumble bees and yellowjackets.  Each female wasp works alone to dig a burrow and provision in with paralyzed cicadas that become the food source for her offspring.  Solitary wasps are not aggressive and they can be tolerated, though most people choose not to!

The wasps that are randomly flying back and forth over an area are the male wasps defending their territory.  Only female wasps and bees can sting.  The males are harmless and the females are too busy working to pay any attention to you.

Cicada killer wasp tunnels may be 12 to 24 inches deep in the ground. Burrows are usually in bare soil and at an edge.  The transitions between sand traps and turfgrass or between flower beds and turfgrass are favorite spots!  There is only one generation per year and populations vary greatly from place to place and from year to year.

When cicada killer wasps cannot be tolerated, control is usually accomplished by putting insecticide dust into the nest opening at night.  Liquid sprays applied to burrows do not work well because they soak into the soil.  Dusts or powdered insecticides work better.

Read more in our online article at

Donald R. Lewis


Department of Entomology

Iowa State University

Ames IA 50011



BROWN AREAS IN YOUR LAWN? IT COULD BE Rough bluegrass (Poa trivialis)

July 26, 2018

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.


What is the Best Time to Seed Lawn Grasses in Iowa?

August 9, 2016

Most of the lawns in Iowa are cool-season grasses.  Kentucky bluegrass is the primary lawn grass.  We also have Kentucky bluegrass/perennial ryegrass lawns and tall fescue lawns, along with fine fescues in the shaded areas.  Tall fescue is generally best adapted to central Iowa and south, whereas Kentucky bluegrass is well adapted to the entire state.

The best time to seed cool-season grasses is late summer.  I generally pick August 15 as the target date for the best time to seed.  Seeding can generally take place as late as the end of September.  Seeding dates in October can work, but the chance of success goes down each day after the first of October.

The primary reason for seeding in late summer and early fall is the germination of warm-season weeds in spring and summer seedings.  Crabgrass, goosegrass, barnyardgrass, foxtail, and other warm-season, annual grasses germinated in spring and summer and out compete our cool-season lawn grasses.  The soil temperatures and moisture are generally better for establishment of cool-season grasses in late summer.  If warm season weeds do germinate in late summer, they quickly die in September and the cool-season grasses have a couple of months to fill in.

If you are planning to establish a warm-season lawn like buffalograss, or zoysiagrass, this should be done in early June.  These warm-season grasses will thrive through midsummer and go dormant in September.

Those who did spring seed this year, probably have a dense cover of crabgrass and other species.  Don’t give up and kill the area.  Assuming that good seed was used in the spring seeding, the grasses that you want are under the annual weed cover.  The annuals will soon die and the cool-season grasses will thrive through the fall and in the spring.  Be sure to put a preemergence herbicide down about the middle of April next year to stop the warm-season grasses that will germinate about the first of May.

For more information on which cultivars to use, fertilization, and herbicide use, see .  Then go to “publications”.  There will be a series of extension bulletins on each of these subjects.

Seed bed:

Using a drop seeder to place seed.

Seedlings emerging.