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Home » Wasps don’t kill beehives.

Wasps don’t kill beehives.

A very common misconception within New Zealand is that wasps (the wasps we have here) are a threat to beehives.

To put it bluntly, this could not be further from the truth and I am willing to state that the wasps we have here are incapable of weakening a healthy beehive enough to cause a serious problem.

The wasps we have in New Zealand, have all been introduced from Europe, the same as our honeybees. Both have co-existed and co-evolved for tens of millions of years and our bees know how to deal with them.

What we are experiencing instead is beekeepers encountering dead, or close-to-dead hives, that seemingly are being robbed out by wasps. Hence, they make the connection that the wasps killed the hive. The same by the way is true for cold weather. Nowhere in New Zealand is capable of producing low enough temperatures to harm a healthy beehive. Many beekeepers around the world successfully overwinter beehives in areas that have freezing temperatures for weeks.

Back to wasps, what can be “threatened” by wasps is severely weakened hives. And I am putting “threatened” in quotes, because by the time they are so severely weakened that wasps are a problem it will generally be too late already.

By blaming wasps as the reason, a beehive died beekeepers prevent themselves from finding the true reason a hive died/was weakened, and thus prevent themselves from improving their skills.

Elimination of a beehive via wasp

Let’s dig a bit deeper and try to imagine a typical scenario on how the “elimination of a beehive via wasp” will typically unfold.

It is late summer, and you have a strong, seemingly healthy beehive, with plenty of stores. Knowing about varroa treatments you do as being told and buy a brand of strips and put them into the hive, as per instructions. Great, varroa mites are taken care of till next season, so let’s forget about them. Assuming that either the strips do not work as advertised (different parties with different vested interests will give different guidance as to why that would be), or that reinvasion after successful treatment played a major role, the mite infestation will increase greatly afterwards.

This will come at a time when the hive reduces its total number of brood cells, rearing less brood, at the same time rearing bees that are longer-living, so called winter-bees. With less overall brood cells that any mite might potentially infest, fewer mites still can create an elevated infestation level. This on-going brood rearing into late summer and autumn causes the infestation to rise, and with it the virus load within the hive will too. Thus, more and more sick bees (instead of longer-living winter-bees) that die quickly will be reared. At the beginning the hive will try to counteract this by increasing the amount of brood rearing the hive is doing this late. A beekeeper might notice the surprisingly strong brood rearing activity and think that the hive is doing very well, not knowing that it has entered a vicious downward spiral. On a closer look this is where one will find quite a few bees with deformed wings, and potentially even spot the odd mite sitting on a bee.

The occurrence of bees with deformed wings is a sever warning sign that the mite infestation (which causes high virus load) has reached a dangerous level and another treatment should be done immediately.

If this chance is passed, the hive will continue on with its downward spiral, with more and more healthy bees being replaced by sickly ones. Seemingly at a sudden point the hive will rapidly start dwindling, which will reduce the amount of brood that the bees that are left can keep warm and thus rear.

Due to the reduced numbers of bees the entrance of the hive will not be guarded as well anymore, and it might be completely abandoned. Other bees will notice that there is a weakened hive with an unguarded entrance and plenty of stores and robbing will start. This does not necessarily need to be the violent robbing that is easily noticed, but can be more “silent” robbing with bees casually entering the hive filling up with honey and leaving again, and can go on for days or weeks, slowly reducing the stores the hive has and causing further stress. Such robbing activity is hard to make out and most beekeepers will merely think that they are witnessing normal foraging behavior. After all you can not tell the bees of one hive apart from the other.

This is where wasps finally come into play. They are after two things: Protein for rearing their brood and sugar (in this case in the form of honey).

Just like the robbing bees they will go after the honey stores of the weakened hive.

This robbing behavior as well as the downward spiral can go on in parallel for a while, until eventually the hive is finished off either by a spell of cold weather or starvation because they ran out of stores. This is part of the reason why the myth that cold weather kills beehives is also very prevalent.

Due to the wasps also looking for protein, they might still be active in the now dead hive after its demise, feeding on the dead bees, and potentially their brood.

And that is where our unsuspecting beekeeper comes back into play. After not checking up on the hive after putting in strips (or maybe once to remove them) he does an inspection because he noticed very little activity or even some wasps entering the hive.

The inspection will then reveal a dead hive with hardly any stores, maybe even signs of starvation, and the only thing that’s still alive in there are wasps which essentially are the clean-up crew.

And this is where the myth of wasps killing beehives comes from.

When facing a dead hive, do not jump to conclusions, but try to do a bit of a forensic examination of what happened to the hive. Obviously do an AFB inspection as well and proceed accordingly if you do find AFB.

Look for brood cells and check the brood pattern that is still there, it will likely be spotty. open a few of the capped brood cells and check what’s inside. You will likely find many pupas with deformed wings. Also have a look at the bottom board, check the dead bees there as well as what’s on the board directly, you will likely find many varroa mites.

Of course it is not always as easy as that and mites are not the only thing that can kill a beehive, but do not jump to conclusions too quickly.

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