Wasps, hornets out in full force

Exterminators keeping busy with calls to remove the insects from Wisconsin homes

FOND DU LAC - Close encounters with stinging insects have reached a peak right about now.

A bumper crop of wasps and hornets has kept exterminators busy with calls to remove swarms and nests from awnings, gutters, decks.

Yellow jackets and paper wasps are most abundant and conspicuous throughout the state, says entomologist Patrick Liesch, who runs the Insect Diagnostic Lab at the University of Wisconsin-Madison.

“The cycle begins with a few wasps who start nests from scratch early in spring and they remain relatively calm and go unnoticed,” Liesch said. “By fall, nests reach maximum size and can contain thousands of family members.”

That’s when they come out in force and are aggressive enough to attack anyone that appears to be a threat to their colony or their dwindling food supply.

Warmer winters and not enough winter kill could be the cause for an increase in these insects, said Casey Siewert, from Diamond Pest Control in Waupun. Yellow jackets like to build in cracks in and around house siding, and if they are far enough in, some can even survive the winter.

“Since these insects are cold-blooded they are seeking heat and that’s why they are attracted to buildings, which radiate heat,” Siewert said.

The unpopular pest can produce new generations every seven to 10 days, so homeowners may see a variety of sizes flying about. Juveniles tend to be the workers while the larger adults remain inside the nest.

Mark Wick, owner of On The Mark Pest Control in Fond du Lac, has fielded some 50 calls this season asking him to come take care of an unwelcome nest that has gotten out of control.

Bald-faced hornets, the largest of the species, are also out in numbers, he said, identifiable by their black and white stripes. Another type seen are

cicada killer wasps, bright orange in color.

“The first thing I tell people is do not seal up the hole,” Wick said. “That could force them to travel inside the house.”

Exterminators, donned in bee suits, inject the nest with chemicals in the form of a dust, aerosol or liquid. Sometimes it takes a few tries to get them all.

In just a couple of months, all the buzzing will cease and most of the invasive insects will be dead, either by starvation or from frost.

“The vast majority will be gone, but certain lone female queens who have mated will make it through the winter and start their own colonies next spring,” Liesch said.