AUGUSTA, Maine — A mild winter and unseasonably warm early spring have created conditions reminiscent of 2010, when an explosion in mite populations killed off many bee colonies in Maine.

Tony Jadczak, state apiarist and bee inspector, is warning beekeepers to monitor for the varroa mite, an external parasitic mite that attacks European honeybees.

“The bees are coming out, but so are the parasitic mites,” Jadczak told the Kennebec Journal. “What I’ve seen in my inspections is elevated mite loads because of the good health of the honeybees. If it tracks like it did in 2010, we’ll have a huge die-off in the fall and winter.”

Maine beekeepers have suffered enormous losses since the parasite from the Asian honeybee was introduced into the United States in the mid-1980s.

And parasitic mites are not the only concern for beekeepers.

Beekeepers and some scientists say pesticides are killing bees and weakening their immune systems, making them more susceptible to pathogens. They say it could contribute to colony collapse disorder, in which all the adult honeybees in a colony suddenly disappear or die.

Bees are vital to U.S. agriculture because they pollinate many flowering crops, including blueberries.

Maine doesn’t have enough bees in the state to pollinate all the crops, so thousands of bee hives are brought in by commercial beekeepers every year.