Robbing Bees: Signs, How to Stop It & the Varroa Risk

Robbing Bees: How to Recognize It, Stop It, and Why a Robbed Hive Spreads Varroa to Every Hive in Your Yard

Robbing is honey bees stealing stores from another colony, and it happens fast: a weak hive can be stripped in an afternoon. Beginners usually see it for the first time in late summer, when the nectar stops and forty thousand foragers with nothing to do find the hive that can't defend itself. It is ugly, it kills weak colonies, and there is a second cost most beekeepers never connect: the robbers bring home mites.

The short version

Robbing: fighting and tumbling bees at the entrance, dead bees on the board, frantic zig-zag flight, bees probing every crack, no pollen on any legs. Stop it with an entrance reducer or robbing screen, a wet sheet over the hive, and no open feeding. Then wash your strong hives for mites, because Cornell research shows a collapsing hive being robbed sends mites to every colony within at least 300 meters. Keep an InstantVap oxalic acid vaporizer ready for what the wash finds.

Robbing vs. Orientation Flights

Robbing	Orientation flights (normal)
Bees fighting, tumbling, rolling on the landing board and in the air	No fighting; young bees hover in calm figure-eights facing the hive
Dead and dying bees on the board and ground	No dead bees
Bees probing seams, cracks and the lid, not just the entrance	All traffic through the entrance
No pollen on any incoming bee	Foragers arriving with pollen mixed in
Frantic zig-zag flight; robbers leave heavy and dip before climbing	Brief, mid-afternoon, over in 20–30 minutes
Shiny sticky smears at the entrance where robbers wipe their feet; wax bits on the board	Clean entrance
Loud, high-pitched, goes on for hours	Quiet

Heavy, frantic traffic at a hive you thought was weak or dead is the classic giveaway. A dead-out with a busy entrance isn't alive. It's being emptied.

What Triggers It

Dearth, above all: late summer and early fall after the flow ends, and early spring before it starts. Add a weak, queenless or diseased colony that can't guard its door, an entrance left wide open, a hive body with gaps, spilled syrup, an entrance feeder, supers left open during harvest, or open feeding in the yard, and you have a robbing event. The strong colonies aren't misbehaving; they're doing what foragers do when the flowers stop.

How to Stop It

Shrink the door. Entrance reducer to the smallest opening, or stuff grass in it. A colony can defend one bee-width.
Robbing screen. A screen that forces bees to enter around the side while robbers beat against the front. Leave them on weak colonies through the dearth.
Wet sheet. Drape a wet towel or sheet over the hive. The residents find their way in; robbers lose the scent trail and give up.
Close it. In an extreme case, hardware cloth over the entrance for a day or two, with ventilation and shade.
Remove the temptation. No entrance feeders, no open feeding, no wet supers or cappings in the yard, seal every crack with tape, keep the honey house bee-tight.
Prevent it next year. Combine weak colonies before the dearth, reduce entrances the week the flow ends, and keep colonies strong so there's no easy target.

The Part Nobody Tells Beginners: Robbing Spreads Mites

In 2019, David Peck and Thomas Seeley at Cornell set out mite-loaded colonies among healthy ones at 1, 50 and 300 meters and tracked what happened as the sick colonies collapsed over the fall. Drifting bees moved a few mites to the closest neighbors. Robbing moved a lot of mites to all of them. As the collapsing colonies weakened they became targets, and the robbers went home carrying the mites. Receiver colonies rose from a mean of 9 mites per 300 bees to 23.5 in under three weeks, with no protection from distance; the sharpest spike was in the colony 300 meters away. The authors' phrase for a collapsing hive was "robber lure."

So the hive you watched get robbed out in September, the one that "absconded," was most likely a varroa collapse, and your strong hives just inherited its mites right as they were raising their winter bees. That is how one bad hive kills three good ones by February.

What To Do After a Robbing Event

Close up or remove the robbed hive so it stops being a lure. Freeze the frames.
Wash every strong colony within the week.
Above 2–3 per 100, treat with oxalic acid vaporization on the fall schedule. With an InstantVap it's seconds per hive, which matters when you have a whole yard to cover before the winter bees are raised.
Wash again in three weeks to confirm.

Tools We Use (and Recommend)

InstantVap Oxalic Acid Vaporizer: the cordless, battery-powered oxalic acid vaporizer we use in our own yards to keep mite loads low, which is the single best defense against every problem on this page. See the Lite, Compact, Original and Turbo. Lorob Bees is the primary US seller, with stateside customer service and a warranty we stand behind.
Mite Monitoring: the Easy-Check mite wash. How to do a wash in five minutes.
Oxalic Acid: EPA-registered EZ-OX.

Happy Beekeeping from the Lorob Bees Team

Written by Rob Pollock

Rob keeps bees in Baltimore, Maryland, and owns Lorob Bees. He built and repaired his own corded oxalic acid vaporizers for years before becoming the primary US seller of the InstantVap, and he still picks up the phone when one needs service. Oxalic acid vaporization is the thing he cares most about in beekeeping, because it's the treatment that keeps hives alive without breeding resistant mites. More about Lorob Bees.

Keep reading: Explore all Lorob Bees beekeeping guides — varroa, oxalic acid vaporization, pests and diseases, all in one place.

Sources

Peck D.T. & Seeley T.D., Mite bombs or robber lures? The roles of drifting and robbing in Varroa destructor transmission from collapsing honey bee colonies to their neighbors, PLOS ONE, 2019
Honey Bee Research Centre, University of Guelph, Robbing Prevention
Honey Bee Suite, How to recognize robbing bees and ways to stop them

General beekeeping information, not a substitute for the product label. Always read and follow the label of any product you use in a hive.