April tends to be one of the better months of the year in the lower Southeast. The seasonal calendar tells us that winter is officially behind us, and the occasional “cold spells” are becoming fewer and farther between, with little worry about hard freezes and such.
But you’d have to have a pretty short memory to let the possibilities of spring fool you into forgetting totally about the winter just passed. It was just plain harsh, despite the criticism from our Northern and Midwestern neighbors who continue to say that Southerners don’t know cold.
During the very worst days of this past winter, with temperatures dipping into single digits and ice clinging to the ground, I kept remembering that line from Shakespeare’s Richard III, “Now is the winter of our discontent…” It’s a damn cold winter that’ll make you remember your Shakespeare.
My first thought, when trying to think of one good thing about our discontented winter, was that maybe the cold was too much for insects, especially the kudzu bug, which has become a scourge of homeowners and farmers alike. And I’ve heard this sentiment from others – that since the winter was so severe, at least by Southern standards, perhaps insects won’t be as plentiful. It was cold enough, after all, to cause a limited amount of agricultural losses, and it was cold enough to close schools, bridges and roads, not once but a few times.
But most entomologists agree that you can’t make such a broad generalization about insect pests in the South.
Scott Stewart, an IPM Extension specialist with the University of Tennessee, says the reason we have more bugs in the South than in other parts of country is obviously because of our warmer environment. However, he adds, not all insect pests are equally affected by weather conditions – some are very tolerant of cold weather while others take a hit during an unusually harsh winter.
But one pest that is very much on the minds of Southeastern farmers these days – the kudzu bug – could be affected, says Xing Ping Hu, an Alabama Extension entomologist. For the past few years, she and a team of researchers have been monitoring overwintering kudzu bug populations, and their conclusion is that there will be fewer of the pests this spring.
The reason, she contends, is the endurance of this past winter.
“We noted in 2013 that some of the bugs emerged out of the dormant status of hibernation too early, used their energy, and died when the temperatures dropped again in early February,” says Hu. “But then warmer temperatures set in, and the insects rebounded.”
Hibernating bugs catch cold
She initially thought the bugs would bounce back just as quickly this year. More kudzu bugs remained in their dormant status, with the ones hibernating underneath thick bark, vines and trees shielded against the ravages cold temperatures.
However, things changed after early February as winter lingered in the Deep South. More and more of the hibernating bugs began dying, says Hu. A survey conducted last month showed that more than 90 percent of overwintering bugs had died, compared to 70 percent in 2013, with males suffering higher mortality rates than females.
“We’re noticing that most of the survivors are still in dormancy – a significant change from 2012 and 2013, when much larger numbers were observed emerging from their long slumber and flying out to mate as mid-March approached,” she says.
Persistently cold temperatures get the credit for this occurrence, says Hu, and the result should be fewer kudzu bugs this spring. But don’t get too comfortable – the bug is a prolific reproducer, and populations may increase rapidly in the summer and fall.
The University of Tennessee’s Stewart says the learning curve continues on kudzu bugs. Both kudzu bug and brown marmorated stink bugs like to overwinter in homes and other structures, so we know some will make it through the winter, he says, and based on its distribution in its native home range, this pest should make it just about anywhere kudzu is common in the South.
“I expect there is a place where only one generation (as opposed to two) occurs each year. This could be a help, but we don’t know where that line is yet,” he says.
And before you get your hopes up regarding other insects, the experts tell us not to expect much change in the typical populations of pests such as cockroaches, fleas and mosquitoes.