University of Florida Extension ServiceUF/IFAS Okeechobee County Extension Service

458 Highway 98 North

Okeechobee, FL 34972-2578

Phone: (863) 763-6469

E- mail:  dfculbert@ifas.ufl.edu

October 10,  2007

Quick Links:   Striped Grass Looper ID     Caterpillar monitoring      Pesticides      References 

 Feature Article - for release the week of October 14, 2007 

Dan Culbert – Okeechobee Extension Horticulture Agent

 

Worms in the Grass 

Last week’s gardening column on the Yellow-necked caterpillar that is chewing up local oaks has opened up a “can of worms.”  Our Master Gardeners have been crawling with all kinds of caterpillar calls in the past week.

Today’s column will talk about one of these critters that came from a local lawn.  This one is worth worrying about, as it’s that time of year to be dealing with turf caterpillars too.  Identification is very important, as we have had a few others creepy crawlies in our local Florida Yards that are not a problem.  And the decision on what if anything to do depends on whom they are.

From Grass to Frass

These were the caterpillars recently  found chewing up a small pasture in Okeechobee.  The Striped Grass Looper can also consume lawns.  Photo: Dan Culbert, UF/IFAS.

One of last week’s office visitors brought in a container filled with a bunch of caterpillars collected from his lawn.  They were generally tan in color, but had some thin stripes of color running the length of their 2 inch long bodies.  A close look at their eyes showed they were striped too!  Our visitor said they have reduced a part of his lawn to a pile of frass – the polite word for what these insects leave behind.

The identification stumped me at first.  I’ve seen and heard of caterpillars that can consume our Florida Lawns, but had not seen these worms.  When disturbed, they had an inchworm-like habit:  “they are kind of loopy,” I said – and that prompted Angela to suggest that maybe they are some kind of looper.

Boy was she right! A little searching around and she nailed it - these crawlies are called Striped Grass Loopers, one of three common caterpillars that can chomp down a lawn.  Alachua County Horticulture Agent Wendy Wilber reports that besides this striped grass looper (SGL), two other lawn caterpillars active at this time of year are tropical sod webworms TSW) and fall armyworms (FA) . These caterpillars all develop into moths, but you normally don't notice the adults unless you are having a severe outbreak.

Common Turf caterpillars  All photos from Weissling & Cisar, UF/IFAS

Striped Grass Looper (SGL) Tropical Sod webworm (TSW) Fall Armyworm (FA)

This insect has a wide range, and is known across the southern tier of the US, throughout the Caribbean and Central Americas and even South American countries of the Pacific coast.  The species that we deal with is known to entomologists as Mocis latipes.

Loopers can be distinguished from fall armyworms by the presence of many fine lines on its head and two pairs of abdominal “prolegs”.  The adult moths are an unremarkable tan brown color with very few markings on their wings.  The adults migrate from south FL to north Florida in midsummer where the eggs are laid and these larval caterpillars pupate in spindle-shaped cocoons that are fastened to grass blades.

UF Turfgrass specialist Eileen Buss has reviewed some research on caterpillars.  She finds that the application of water-soluble, inorganic nitrogen fertilizers cause rapid grass leaf growth,  and this increases the chance of  caterpillar problems.  Female moths that are ready to lay eggs are attracted to the lush succulent leaf growth.  So its probably best lay off the high nitrogen fertilizers if you want to reduce the chances that your lawn becomes lunch for a looper.

The "loopy" inchworm habit of the Grass looper is seen in this picture. Photo (c): Grant Gentry, Tulane University.

A comparison of the head capsules of the Striped Grass looper (right) and the Fall Armyworm (left) shows the striped pattern of the SGL.  Photo: UF/IFAS

The adult moth of the Striped Grass Looper. Photo: Lyle Buss, UF/IFAS

Looking for trouble

This shows how to use as soap solution to help look for caterpillars in turf . Count the number of caterpillars that come up from within a 1 square foot area to measure the severity of the infestation.  If more than 3 SGL worms (or 10-20 TSW) are found, its time to apply an insecticide. Photo: UF/IFAS

To get a sense for how bad an infestation is before your lawn completely disappears, monitor for the caterpillars.  Look for chewed leaves and follow-up the search with a soil drench.  Drench the soil with a soap solution of two tablespoons of dishwashing soap in two gallons of water; pour this solution over a square yard of grass and watch for pests crawling out of the soil and on to the grass blades.

If you are able to identify as few as three loopers or armyworms per square foot, it’s time to take corrective action.  For the tropical sod webworms, the threshold is much higher – wait to treat until levels are as many as 10 to 20 tropical sod webworms square foot.

There are many beneficial insects that feed on these caterpillars.  Dr. Ron Cave, a Bio-Control expert at the UF Research Center in Ft. Pierce, found that in Honduras there are as many as 31 different kinds of predators and parasites that can consume this species.   There are not as many as that here, but ants, ground beetles, rove beetles and wasps can all eat these lawn-munching caterpillars.  Bottom-line: try to use pesticides as a last resort, and use the least toxic method first.  

If you catch the caterpillars when they are still young, a product containing Bacillus thuringiensis or “Bt” will work.  Some trade names for products with this material are Dipel, Thuricide or Safer’s Caterpillar killer.   If the problem is ongoing, you will need to spot treat with an insecticide like Scott’s MaxGard or Sevin. Insecticide use should be ideally timed for about two weeks after peak moth activity noted, and is most effective in the early evening when larvae begin feeding.

Baker County CED Mike Sweat also says these are a problem in pastures.  The striped grass looper damage is similar to the chewing on forages done by fall armyworm.  And like the fall armyworm, female moths prefer to lay their eggs on tender new growth.  Population studies have found that some kinds of pasture grasses are favored by the loopers, so get with us for the research results if these insects are affecting your business of growing pasture grasses.

I’ve placed more information on our Okeechobee web page, http://okeechobee.ifas.ufl.edu.  If you need additional information on the Striped Grass Looper or other turf caterpillars, please email us at okeechobee@ifas.ufl.edu or call us at 863-763-6469.  Local residents can stop by our office at 458 Hwy 98 North in Okeechobee, and visit our Okeechobee County Master Gardeners from 1 to 3 PM on Tuesday afternoons.  GO GATORS!

-30-   

Trade names, where used, are given for the purpose of providing specific information. They do not constitute an endorsement or guarantee of products named, nor does it imply criticism of products not named. The Florida Cooperative Extension Service - Institute of Food and Agricultural Sciences is an equal opportunity/affirmative action employer authorized to provide research, educational information, and other services to individuals and institutions that function without regard to race, color, sex, age, handicap, or national origin.  Florida Cooperative Extension Service / IFAS / University of Florida.  Larry A.  Arrington, Dean. Last update: 10/12/2007.  This page is maintained by Dan Culbert 

References

Buss, E.A. and  Meagher, R.  Lawn Caterpillars (ENY-352).  Gainesville: UF/IFAS Extension Service, April 2006. http://edis.ifas.ufl.edu/IN608  

ibid.  "Nibbling and notching caterpillars in Florida turfgrass" . Florida Pest Pro. p. 14-17.  2005. http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=185226

Cave, Ronald D.  Inventory of Parasitic Organisms of the Striped Grass Looper, Mocis latipes (Lepidoptera: Noctuidae), in Honduras.        
The Florida Entomologist, Vol. 75, No. 4 (Dec., 1992), pp. 592-598.  http://arsserv0.tamu.edu/research/publications/publications.htm?seq_no_115=194681

Gentry, Grant. Mocis latipes [Guenee] Small Mocis (Louisiana Lepidoptera website).   http://www.tulane.edu/~ggentry/LAleps05/species/Noctuidae/Mocis/Mlatipes.htm 

Sprenkel, R. Insect Management in Pasture. Gainesville: UF/IFAS Extension Service, 10/2007. http://edis.ifas.ufl.edu/IG061 

Sweat, Mike.  "Insect Management in Pastures & Hayfields".  In: Northeast Florida Beef and Forage Group (Newsletter).  MacClenny, FL: UF/IFAS Baker County Extension Service,   4/4/2007. http://nfbfg.ifas.ufl.edu/newsletter/April%202007.pdf 

Weissling, T.  &  Cisar, J.  Caterpillars (Sod Webworms, Loopers & Armyworms)  Fort Lauderdale:  UF/IFAS Fort Lauderdale REC,  http://flrec.ifas.ufl.edu/pdfs/Caterpillars.pdf 

Wilber, Wendy. "Tropical sod webworms feast on lawns."  Gainesville: Gainesville Sun, September 5, 2007. http://www.gainesvillesun.com/article/20070906/COLUMNISTS/709060304/1023/COLUMNISTS