EL PASO COUNTY, Colo. -

The recent invasion of the pine sawfly hasn't been good for owners of ponderosa pine trees but it has been good for pest control businesses kept busy by the demand for service calls.

Brendan Shank of Bug-Free Tree & Shrub Spraying in Security said he has responded to 20 calls daily for the past three weeks.

"I've been doing this since 1992 and we've never had an infestation like this before," he said.

Shank believes the insect is attacking trees stressed by drought and is reproducing in greater numbers because of the wetter-than-normal summer.

"We actually started getting calls last summer in Calhan," he said.  "Now it's moved east and north to Peyton, Black Forest and Elbert County.  So far, it's staying out of the city and affecting only rural areas."

Shank said he spent four hours Wednesday spraying 90 trees at the Peyton ranch of Sharon Bennett.

"I first noticed (the sawflies) Tuesday," she said.  "I thought my trees didn't look right.  We found there were tons of (larvae) covering them, devouring them."

However, after Shank sprayed the trees with an insecticide called Astro, most of the larvae lay dead on the ground under the trees.  Only a few dead or dying larvae remained on the branches.

Shank said Astro is safe enough to use as a flea repellent on dogs and that it's effective only when sprayed directly on feeding larvae.

Many tree owners fear that their trees will die from the damage inflicted by sawflies, but Shank said the trees should gradually recover once the infestation is removed.

"I hope we've seen the last of (the sawflies)," Bennett said.