White insects floating in Knoxville air are aphids

White insects floating in Knoxville air are aphids

The white insects on this leaf are wooly hackberry aphids. The white insects on this leaf are wooly hackberry aphids.

September 27, 2004

6 News Reporter

KNOXVILLE (WATE) -- Pesky, white insects seen around Knoxville recently are called aphids and they're pretty much harmless. But an insect you could call their distant cousin is doing a lot more harm in the Great Smoky Mountains.

Hemlock trees line the streams of the Smokies and, as spokeswoman Nancy Gray explains, "...shade the water, therefore protecting the temperature for the cool water species like the native brook trout and other aquatics that live in the streams."

An Asian sucking insect called a Hemlock Wooly Adelgid is sucking the nutrients out of the hemlocks, killing them in about three to five years.

"In the spring, it's very apparent that if you turn over the branch on the underside you can see a white cottony waxy substance."

UT entomologists are breeding Asian predator beadles to kill off the cotton-like insects.

In Knoxville, another Asian sucking insect is infesting trees. But the wooly hackberry aphids are far less harmful to trees.

"They don't cause any appreciable harm," said David Vandergriff. "It's a sucking insect but in particular this time of year, they're fixing to loose their leaves anyway so they're of no consequence to the trees' health."

Where there's one aphid, expect hundreds more so they're a bigger nuisance. "They feed on plants and they secrete honey dew, which is a sugary sap. As a result of their feeding on the plant, once that sap goes through that insect's body and goes into the atmosphere, it turns black and molds," Vandergriff said. 

Get used to seeing aphids in Knoxville. Entomologists say it's going to take a winter freeze to get rid of them.

As for the adelgids in the Smokies, rangers say it's going to take an estimated 7 million predator beadles to save the Hemlock trees.

The park is raising funds to breed more predator beadles through the Friends of the Great Smoky Mountains organization.

Neither insect is harmful to people but there are insecticides available to kill both.

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