Cotton Insect Newsletter Vol. 21, No. 5, June 18, 2003 Call 1-877-629-1474 for Cotton Insect Hotline

Cotton Situation:  Rainfall has been abundant throughout most of the state this week. Temperatures at night and during the day have been just what cotton plants need for growth and development.  We are seeing more fields with plants that are starting to put on squares.  Insect Situation:  As I mentioned last week, thrips are no longer causing any economic problems in cotton.  There are still a few cutworm problems and I heard a couple of reports about false chinch bugs.  Eggs are now being laid in some of the older cotton by bollworm and budworm moths.  Larvae will feed in terminals of pre-squaring cotton.  Once squares begin to develop, they will move from terminals into the squares.  When you see plants with “dirty terminals,” spread the developing leaves apart to locate the tiny worms.  Varieties of cotton containing Bt toxin should not have economic problems at this time of year.  In fields planted with conventional varieties, scouts will need to determine the numbers of small worms per 100 plants, and when squares are present, determine the percent damaged.  When 15 small larvae are found per 100 terminals, or 20% of squares are damaged, an insecticide treatment may be needed. Plant bugs (tarnished plant bug and cotton fleahopper) often attack cotton plants that have started squaring.  Economic problems are rare, but strange things happen sometimes in cotton fields.  For example, there would be a higher risk if the following conditions were met: an early maturing variety was planted late, an average of one or more plant bugs was found per row foot using a beat cloth, and 25% of pinhead squares had been lost.  Speaking of eggs, there are lots of eggs that may be found in a cotton field besides the bollworm/budworm type.  For example, beet armyworms produce eggs about the same size as bollworm eggs, but they are laid in clusters rather than singly.  Stink bugs lay barrel-shaped eggs in clusters.  Lady beetle eggs are bright yellow in color and are laid in clusters.  Big-eyed bug eggs are often found on cotton plants at this time of year.  These predators are very important in helping to regulate June infestations of budworm/bollworm.  Big-eyed bug eggs are cigar shaped with a pinkish coloration.  They will often be found in terminals when a scout is looking for small bollworms and eggs. COTTON LISTSERVER:  I have received quite a number of email messages from those of you wanting to join the cotton listserver (mroof@clemson.edu).  The listserver was designed to send information about cotton insect pests to a group of folks that are really interested in the subject.  Most of the people who subscribe are also checking cotton fields from time to time.  It would be really helpful if some of you would send some updates out to our cotton group when you spot an insect pest problem in the field.  If you want to send a message to everyone, all you have to do is type To: COTTON-L@CLEMSON.EDU.   Mitchell Roof  Extension Entomologist

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