Utah has been hit by two insect pests, the Russian aphid and the gypsy moth. Both are to be fought by aerial spraying, and the counter-attack on the aphid poses a danger to humans and wildlife.

The gypsy moth is native to eastern states, where Pennsylvania, West Virginia, Maryland and New England are infected. "It's a defoliator," said Dave Holland of the U.S. Forest Service, Ogden. "It chews leaves off of trees. There's not much it doesn't attack."The moth strips everything from aspen to oaks, from fruit trees to pines.

Now the gypsy moth has appeared in the Salt Lake canyons, particularly Millcreek.

"This is the first time it's shown up in Utah," Holland said. "Since it's a quarantine pest, we have to make an attempt at eradicating it."

A steering committee has been set up among state, federal and local agencies. Its next meeting is planned for early December.

Much of the land infested belongs to the U.S. Forest Service. Because federal funds will be used in the spraying, an environmental assessment will be released for public comment.

"We're right now putting the plans together to do a treatment project this spring that would include an aerial application," Holland said. Most likely, a bacteria would be sprayed.

This bug is a stomach poison for the kinds of moths and butterflies feeding during the short period that it is effective. Another possible spray is dimilin, a synthetic growth regulator, which could kill more insects than the bacteria would.

Dimilin "does affect some aquatic insects," but regulations prevent its use over open water. He does not believe it could cause problems for wildlife, because it would be used in a small area and the spray is fairly specific.

But the sprays already used against Russian aphids are much more dangerous.

The Russian aphid devours grasses, including winter wheat. Last year it was such a serious problem in Colorado that 1.2 million acres were sprayed against it. Idaho is infected from Boise through the Snake River plain.

"They just started really noticing it in Utah in November, and they started spraying for it," said George Wilson, a biologist with the Utah Division of Wildlife Resources, Ogden.

So far, the spraying has taken place on private land from the Idaho State Line to about Salt Creek or Corinne, he said. "That's where the problem has been."

"There're three different pesticides that can be used. The ones that they're using in Utah have been disiston and cygon . . . They're dangerous enough to the point that you should wear protective clothing if you go into the field within 24 hours."

How dangerous are the chemicals? Wilson said the applications are "done by aerial spraying because of the safety. It's not safe enough to be applied by hand."

If geese, pheasants or ducks were to eat leaves that were recently sprayed, "it could kill them," he said.

In places where the chemicals have been used extensively, as in Colorado, "you're bound to have a significant impact on wildlife."

Also, anyone eating the internal organs of an animal that had ingested the pesticide could be asking for medical trouble. The organs could concentrate the poison.

Even deer could be poisonous. "But then again, you'd have to eat the organs and the deer would have to be exposed to a tremendous amount of it."

So far, only about 2,000 acres have been sprayed and no dead birds or deer showed up.

"The problem's going to come this spring," Wilson said. There may be large spraying projects then.

"The magnitude of the scale is what scares me. When you spray 1.2 million acres with a pesticide, like they did in Colorado . . . you're going to be killing wildlife."

Depending on when it happens, nesting birds could be killed. "Whenever you have aerial spraying, you have drift," he warned.

Bob Ruesink of the U.S. Fish and Wildlife Service in Salt Lake City said a compound used against the aphid is fairly toxic and persistent in the environment.

Agencies have formed a steering committee and studied the possible impacts of a relatively benign bacteria to be used on public land against the moth. But through some quirk in the law, private farmers are free to blast away against the aphid with dangerous chemicals.