Millions of honey bees are dying in the war against Zika

The fight to stop the spread of Zika claimed millions of unexpected casualties this week after Dorchester County, South Carolina, sprayed aerial pesticides in a bid to control mosquito populations. Soon after the pesticides were released over the area on Sunday morning, huge numbers of honeybees started crawling out of their hives in a bid to escape, dying just outside the entrance.

The vast majority of the Dorchester County bee deaths happened at Flowertown Bee Farm and Supply, which lost 46 hives, or about 2.5 million individual honeybees. Juanita Stanley, co-owner of the business, described seeing bees poisoned as they tried to drag the dead out of the hive. "Now, I'm going to have to destroy my hives, the honey, all my equipment. It's all contaminated", Stanley told CNN, adding: "Today, it stinks of death. Maggots and other insects are feeding on the honey and the baby bees who are still in the hives. It's heartbreaking."

Stanley was never notified of the planned insecticide spraying, though county officials said they had reached out to local businesses on the mosquito control registry before they sprayed and simply forgot to reach out to Flowertown Bee Farm and Supply. Local fire captain Andrew Macke, who like many other hobby beekeepers was never on the registry, also lost both his hives this week.

Colony collapse, a phenomenon where worker bees suddenly vanish from hives, leaving the colony unable to function, has been a longstanding concern among beekeepers in the US and elsewhere. In the EU, bans on certain pesticides have been put in place to protect falling pollinator populations and there have been calls for similar legislative action in the US.

But the pattern seen in Dorchester is different and stands out from the larger bee decline. Heaps of dead bees piling up outside hives points to acute, immediate pesticide poisoning. What's more, the pesticide used by the County, Naled, is a well-known insect neurotoxin - meaning it is as effective against bees as it is against mosquitos. Despite these potentially damaging side-effects, the Centers for Disease Control and the Environmental Protection Agency still recommend the use of Naled for Zika control.

Though there have been only four cases of Zika in Dorchester County, all of them travel-related, the same insecticide has previously been used in the area to kill mosquitoes and control other vector-borne diseases. But previous spraying has happened along roads from trucks and with sufficient warning, making it much easier for honeybee keepers to protect their tiny livestock from its powerful toxic effects.