Constable: Bees have ways to cope with winter
Last January, the rusty patched bumblebee became the first wild bee in the continental United States to achieve the dubious distinction of being added to the endangered species list. Between misguided people who kill the valuable pollinators in the summer and our recent cold spell, I feared the species might not survive until spring.
But May Berenbaum, a professor and head of the Department of Entomology at the University of Illinois at Urbana-Champaign, says the rusty patched bumblebee approaches winter differently than say, humans.
"With bumblebees, everybody dies -- except the queen," Berenbaum says.
Before the cold weather sets in, the queen bee mates and feasts, packing on winter weight. Then she burrows into the earth and enters diapause, a form of hibernation. With luck, she stays warm enough to emerge in the spring and lay her eggs.
"She essentially raises a brood of offspring by herself," Berenbaum says, noting a bumblebee nest usually contains 300 to 500 bees. Because the rusty patched bumblebees are hard to spot, no one knows if there are more or fewer of that breed since they became endangered. But bumblebees are native to North America, have a fuzzy fur coat of sorts, and have endured cold winters before.
Honeybees, the kind nourished by suburban beekeepers, need a different approach to winter.
"No honeybees existed in North America until humans brought them over," Berenbaum says of the winged European immigrants. Living in hives above ground, honeybees spend the winter as many of us did for the first week of 2018 -- shivering. A cluster of 30,000 to 50,000 honeybees will form a ball of bees and vibrate to generate heat, Berenbaum says. Even during our below-zero temperatures, an effective bee cluster can live off stored honey and maintain a hive temperature of about 60 degrees in the center.
"The bees take turns being on the outside," Berenbaum says.
Bees are threatened by pests and toxins, and research into declining bee populations continues. A study by Berenbaum and postdoctoral researcher Ling-Hsiu Liao published Monday in the journal Scientific Reports found that some bees prefer to collect sugar syrup laced with a fungicide that can contaminate hives and mess with the bees' ability to metabolize pesticides. Winter is a more natural threat.
Since honeybees were brought here from Europe, they generally know how to survive the elements. The Africanized honey bee, brought to Brazil by scientist Warwick Kerr in 1957, can't survive this far north, Berenbaum says.
Ice crystals are the biggest threat to the bodies of bees and other insects. Monarch butterflies escape that danger by migrating. Asian ladybugs and other insects try to hang out inside warm suburban houses, which is why it is not impossible to get a mosquito bite in your bedroom during the winter, Berenbaum says. Some insects "make their own antifreeze in their equivalent of blood," she says. Then there are the insects made for winter. Snow fleas (tiny insects that aren't really fleas) and winter stoneflies survive through our winters and can sometimes be seen moving on top of snow banks. Rock crawlers, a wingless insect found in the U.S. only in the peaks of the Rocky Mountains, is so adapted for the cold that "the heat of your hand can kill them," Berenbaum says.
There are nearly as many ways to survive winter as there are insects. In spite of the springlike forecast with temperatures topping 50 degrees on Thursday, we humans will get another chance to work on our survival skills this weekend when overnight lows are expected to be in the single digits. You might want to go into hibernation, huddle with a loved one, shiver a bit and try a hot cup of tea with honey.