Why are There Dead Bees in Front of the Hive?
Ask the Expert!
Marlin Hendricks asks:
I have a full, active Warre hive — 4 boxes — but lots of dead or dying bees on the ground right in front of the hive. Several hundred per day for the last 2-3 weeks. Some are dead; others are ‘shivering,’ weak, unable to fly, maybe walking a little or on their backs kicking. No deformities, no mites that I can find. Any ideas?
Rusty Burlew replies:
Several things can cause large quantities of bees to die in front of a hive, including some diseases such as nosema, tracheal mites, and viruses. However, your description sounds to me like pesticide poisoning.
It isn’t easy to diagnose these conditions without laboratory analysis, and even then, you have to tell the lab what you want them to look for. In the end, the analyses are often better at telling you what is not the cause of death rather than what is.
I lean toward pesticides for several reasons. First, it sounds like you have a large and otherwise healthy colony. Second, many of the common pesticides overstimulate the central nervous system, causing shivering, kicking, and what may appear like stumbling. In addition, it’s the time of year when people—especially those not trained, such as homeowners—spray their flowers to control bugs.
Honey bee colonies are often hit hard by pesticides because of their dance language. One bee finds a food source and tells her nest mates where it is. Many may go there to collect the pollen or nectar. Meanwhile, the homeowner sees all these “bugs” on his or her flowers and sprays them. The bees that come in contact with the poison, whether by ingestion or touch, often make it back to the hive before they die. They may try to get inside and be rejected by wary nest mates, or they may decide not to enter to avoid spreading the poison to others—a form of altruistic suicide.
The result of all this is a pile of dead or dying bees right in front of the hive. One common symptom of pesticide poisoning is an extended proboscis (tongue). Extension of the proboscis is a natural reaction to poisoning, much like vomiting in mammals. If you sort through the dead and find many extended tongues, it will add weight to the pesticide theory.
Many colonies can recover from a poisoning event if only a portion of the bees goes to the treated plant. The population will take a hit, however, and it may lower your overall honey production. It’s nearly impossible to tell the source since honey bees travel so far and pesticide use is so common.