Good news for bees as numbers rise and mystery malady wanes

check for mites, we keep our bees well-fed, we communicate with farmers so they don’t spray pesticides when our hives are vulnerable. I don’t know what else we can do.”

Environmental groups have expressed alarm over the 90 percent decline during the past two decades in the population of pollinators, from wild bees to Monarch butterflies. Some point to a class of pesticides called neonicotinoids as a possible cause, a link rejected by Bayer AG and other manufacturers.

In the USDA study, beekeepers who owned at least five colonies, or hives, reported the most losses from the varroa mite, a parasite that lives only in beehives and survives by sucking insect blood. The scourge, present in the U.S. since 1987, was reported in 42 percent of commercial hives between April and June this year, according to the USDA. That’s down from 53 percent in the same period one year earlier.

Among other factors, beekeepers said 13 percent of colonies in the second quarter of this year were stressed by pesticides, 12 percent by mites and pests other than varroa and 4.3 by diseases. Bad weather, starvation, insufficient forage and other reasons were listed as problems with 6.6 percent of hives.

As beekeepers have worked to improve hive conditions, the syndrome has waned as a concern, said May Berenbaum, head of the entomology department at the University of Illinois and a winner of the National Medal of Science.

“It’s been more of a blip in the history of beekeeping,” she said.