Expert: Now Is the Time to Control Caterpillars

The Grayson-Jockey Club Foundation issued an advisory concerning control methods for Eastern Tent Caterpillars, which have been linked to mare reproductive loss syndrome in 2001 and 2002.

Prof. Dan Potter, an entomologist at the University of Kentucky whose research has been funded in part by Grayson-Jockey Club, said on April 3 that "the window for caterpillar management has just opened, and now through the next week or so is the ideal time for control actions."

Potter said the options are:

"1) treat infested trees with a foliar spray. The two products that we have evaluated are Talstar (a pyrethroid insecticide) or Dipel (a microbial insecticide).

"Talstar is very fast acting, gave us near 100% control, controls all sizes of caterpillars, and we got at least a week's residual from a single application. One application should do the job now that all of the egg masses have hatched.

"Dipel (Bacillus thuringiensis) gave us decent control (75% or so). It was quite effective against the small larvae but less so against the large ones. Its residues do not last as long as Talstar's.

"2) inject the trees with bidrin (Inject-a-cide B) within the next week. We found that this was quite effective so long as the larvae were less than half their full size. The injection must be done by the Mauget system by a certified applicator."