Weather put a damper on Wisconsin bug infestations in 2004

Common wisdom might hold that a wet summer might make for a bumper crop of insect pests, but Wisconsin’s damp summer actually suppressed some of the bugs that bug us the most, according to a UW bug specialist.

“This is about as quiet a year as you can get,” says Phil Pellitteri, entomologist in the College of Agricultural and Life Sciences, blaming the dearth of insect infestations on the monsoon-like rains earlier this year.

Insects such as the Asian lady beetle and the Japanese beetle, he says, were down in numbers. These insects tend to do better in drought conditions. And gypsy moth populations were kept low by their natural fungal enemy, Entomophaga, which thrived in the wet conditions.

Mosquitoes were up this year but not as much as expected with so much rain, Pellitteri says. The repeated storms helped to keep the numbers down by washing away the larvae.

The rain in the spring didn’t thwart all insects, though, especially those that live indoors.

“Bedbugs continue to be an issue,” says Pellitteri. “I used to see one or two cases a year. Now there are weeks I’ve seen three to four cases.”

These insects that tend to reside in mattresses and other furniture have been an increasing problem for many people. The reason for this, Pellitteri says, might be a direct result of integrated pest management. “Because we don’t use residual insecticides anymore,” he says, “we’ve become susceptible.”

But bigger than bedbugs this year were mites, Pellitteri says. He even named them the bug of the year.

Spider mites were rampant on conifers in the spring, he says, and white ash trees had a heavy infestation of gall mites, as well. He also discovered two species of mites that had never been described before in the Madison and Green Bay areas.

But Pellitteri says the biggest problem he continues to notice is insects moving out of their normal zones, whether from other parts of the United States or other countries. Importation of products to the state tends to bring along stowaways that then take over their new habitat.

He also says that global warming may be the cause for so many insects moving into Wisconsin that weren’t here before.

“I’d swear the government moved us to Missouri three years back and didn’t tell us,” Pellitteri says. “We continue to see insects extending their range farther north, and that is not going to stop unless we see 30 below.”

As for what the insect situation will be like next year, he says, “It depends on what happens with the weather. It’s way too early to predict that yet.”