Public reminded of proper insecticidal use for elm spanworm

The Department of Environment and Conservation is reminding the public that Btk is the only insecticide that is registered in the province for use to control the elm spanworm. Officials have received several phone calls from people inquiring about what products to use to control the pest.

This is a period in which residents in the St. John�s area are experiencing elm spanworm on their property with moderate to severe defoliation and a lot of bug feces coming down from the trees. As well, it is a time when the larvae start to descend from higher tree branches to lower branches or descend onto property. Larvae have been feeding for the past five to six weeks, and many are preparing to enter the pupal, or resting stage.

Btk is most effective when larvae are in their first instars (smallest). Btk has to be applied when larvae are actively feeding, and applied so that all foliage is thoroughly covered. Rain washes Btk off the leaves and sunlight breaks it down within a short period of time, approximately one to two days.

If someone is planning to use Btk at this time to try and combat the elm spanworm, the department advises that given the current stage of the larvae, the effectiveness of the insecticide may be reduced. Homeowners may not be satisfied with the results, which they should consider before application.

Department officials note that while the elm spanworm is a nuisance pest, it will not kill or seriously damage healthy trees.

To date, elm spanworm activity has only been reported in the St. John�s area.

For more information, contact Karen Ryan, Pesticides Control Manager, (709) 729-3395.

2004 07 23                                      12:30 p.m.