A large amount of supercedure cells should have tipped us off.
Back in early October we did one last check of our bee hives. One of our hives was doing phenomenal. Lots of brood, lots of food for the winter. But one thing that was kind of bothering me was that there was a bunch of supersedure cells. At first I was thinking they were getting ready to swarm which is odd because of the time of year or that there was something wrong with the queen, however based on her brood pattern things seemed healthy.
However, not 3 weeks later we noticed a large drop in activity in that hive almost overnight. We thought maybe it was because it was colder and they were staying in the hive to regulate the temperature. Plus we were still seeing some bees come and go.
We went in this past week just to check the hive only to find the colony had completely collapsed. Not only that, but there was a very large pile of dead bees in front of the hive. I’m kicking myself now for not following my gut early on and checking them. If I had I would have been able to send in a sample of the dead bees and a sample of pollen to determine what had killed them. However, I have my suspicions and they are pretty strong.
The amount of supersedure cells, the nearly overnight collapse of what seemed like a healthy colony and the pile of dead bees outside of the hive point to pesticide poisoning. There are a number of pesticides that are very toxic to honeybees but are commonly used in urban areas such as malathion and Sevin (along with many others that can be used specifically for bees such as Spectracide Bug Stop). Even organic pesticides, such as Permethrin, can create problems for bees as it is highly toxic to them. We avoid the use of pesticides (except for regular Sluggo which is non-toxic to non-target species) but since bees travel up to 3 miles away there just isn’t any way to control their exposure.
Unfortunately pesticides can dissipate fairly quickly so it’s too late to test the pollen.
So if you’re concerned about the plight of pollinators double check that bottle of pesticide’s active ingredient before you spray it.
Hi Rachel,
Bummer! Always a sad day when a hive goes down. We had a colony die of pesticide poisoning several years ago, and the symptoms were extremely dramatic. In our case, the poisoning was acute. Over the course of three days, the entire colony died. The bees were literally surging out the front entrance, writhing and twitching, with their hind legs paralyzed. The end result was a pile of dead bees out front, and pile of dead bees on the bottom board. There was no time for these bees to build supercedure cells.
We’re intrigued that you saw a solid brood pattern back in October alongside the supercedure cells. A few question that come to mind: was the brood at that time of all ages, or were you just seeing a good pattern of capped brood? How many frames/boxes was the brood nest? Were you monitoring for mites? A large mite population could also have bought your hive down and caused the pile out front. In our experience, when a colony is large, we haven’t always noticed declining activity until the very end.
Are you sure the supercedure cells were current? It seems like if these cells were active/viable many more bees would be clustered around them to attend to and warm the larvae. If the cells were old, it’s possible your queen was doing fine and the current collapse is a separate issue.
Kelly was in touch with Eric Mussen, the retired Extension Apiculturist from UC Davis, who told her that in a strong colony, as foragers exposed to pesticides die, hive bees transition to foragers and are likely to choose different sources for their nectar and pollen. His opinion was that strong colonies can usually withstand acute pesticide exposure.
Hope the rest of your bees make it through the winter and your neighbors in a three-mile radius go organic!
Sarah and Kelly
Hi Sarah and Kelly!
Thanks for your comment. To answer your questions when we checked on them there was a good mix of ages in the brood. From eggs to larvae to capped. There were two deeps that each had 6-7 frames filled with brood. We do monitor for mites and use integrated pest management which has worked very well for us keeping varroa counts down. The picture posted is just from the internet since I didn’t take any when we last checked. The cells weren’t there the time before when we checked them. The dead hive has capped queen cells in it. It also has dead emerging bees and dead larvae.
The pile of bees in front of the hive is very large, like all of the bees that were in there when we last checked on them were now dead on the ground. There also weren’t any other “normal” hive pests that we see with an empty hive sitting full of honey. No ants (usually a huge problem for us) and no wax moths. No spiders even.
Great post.