The Small Hive Beetle, often referred to as SHB, is recognized by many beekeepers as a serious threat. It was introduced into the states, via Florida, in the 1990's from South Africa. While originally limited to certain states in the US, it has now spread to many others.
SBH is a brown or black beetle and its larvae can grow to around 11 mm. Adults can live up to six months, with females laying up to 2,000 eggs in their lifetime. The larvae, as we will see, is the main source of damage due to its appetite for everything in the hive. Here is a video that shows the larvae.
Finding a beetle or two in your beehive isn't particularly unusual. Indeed, most types of beetles will come and go in small numbers, without any issues.
The Small Hive Beetle is different.
Consider these facts:
Within a beehive that is pretty much everything! That's pretty bad for the bees. But it doesn't stop there.
SHB larvae will feast on the contents of the hive for up to 16 days, as they mature. Then they will leave the hive to pupate, often in the soil right under the hive.
So even when the larvae have left the hive, they are still a problem waiting to happen. Why? Because when the adult beetle emerges from the soil after about 4 weeks, it heads for the nearest hive. And that hive is right above! There they lay eggs and the cycle continues.
Here's another less-than-appealing thing to consider. The beetles defecate in honey! If that's not bad enough - for obvious reasons related to what you might like to serve on your toast - it also makes honey in the hive ferment, causing it to ooze out of the comb.
SBH = bad news!
Stronger colonies can often defend themselves against SBH, as we will see. However, there is a real threat with weaker colonies, which may eventually just get up and leave the hive. The number of beetles can rise quickly, reaching as many as 10,000.
There can be a fascinating dynamic between bees and SBH. The beetles will search for cracks and crevices in the hive. Since the beetles are too tough to attack directly or to sting, bees often respond by trapping the beetles in confinement areas they build with propolis. The bees then "stand guard", making sure the beetles can't escape. Amazingly, beetles can be held captive this way for months.
But that's not the end of the story. When confined in this way, the beetles have another fascinating trick up their sleeves.
Studies have indicated that the beetles can reach out of their confinement area and "tickle" the bee. This is a re-enactment of what bees do naturally when they use this technique to "beg" for food from other bees. This behavior by beetles has been seen to work, and a guard bee can release a drop of honey for the beetle to eat. Here's an extraordinary video showing this (see around the 35 second mark).
In general, bees can cope with the population of SHB on their own and assign workers bees to take care of the issue, using the bee prisons mentioned above. However, the smaller the colony the less likely they are to have sufficient numbers to defend against SHB.
An example of this, is after a package of bees or a nuc has been installed. Another is after a swarm occurs. In all these cases, the number of bees may not be sufficient to withstand the beetles, allowing their numbers to reach a critical point, from which they can overwhelm the hive.
Adding too much space - by adding additional honey boxes - is also a potential problem. In this situation the beetles have the opportunity to find locations well away from the active colony, expanding their numbers without attention from bees.
In small numbers, SHB may not be easy to detect. Aside from relatively few to spot, they are quick to move, and dislike light. There is a reasonable chance that they have hurried out of eyesight when you gracefully and calmly open your hive.
One way to check for SBH during an inspection is as follows:
Another sign of SHB is the presence of comb that is slimy, or honey fermenting and oozing from cells. Once this spreads it becomes the most obvious way to identify SHB, such is the mess in the hive, as illustrated in this video.
As with everything in beekeeping, prevention is better than cure. The importance of a strong, healthy colony can't be overstated.
Hives in bright sunlight are less likely to attract SHB. Ensuring there is not too much space in the hive is important too, so don't add boxes before the bees are ready to fill with honey. Also, avoid the use of worn, warped or cracked hive components, which offer SHB the cracks and crevices they need.
The tendency for larvae to fall under the hive is something the beekeeper can use to his/her advantage. The larvae will normally pupate in the soil, as we have seen. You can stop this cycle in its tracks by “booby-trapping” the soil with invective nematodes (Steinernematidae & Heterorhabditidae genera).
When the larvae burrow into the soil, the nematodes burrow into the larvae and vomit stomach bacteria into the larvae’s body cavity (delightful thought, eh?). These bacteria will turn the insides of the larvae into an icky rotten goo in just two days. The nematodes eat the goo and lay eggs.
The cycle begins again and very quickly (the nematode cycle, from infecting the larvae to new nematodes emerging, takes only 48 hours) the small hive beetles are no longer a problem.
For use in the hive, various mechanical traps are available. They are often designed to result in the drowning of the beetles. Some of the more popular ones are called the Hood, West, Freeman and Sony-Mel traps and the creatively-named AJ's Beetle Eater.
As an example, here is a video that illustrates how to install the Freeman trap.
For those so inclined, chemical treatments are an option. Chemical treatments in beehives is strictly regulated and in many states CheckMite+ is the only approved chemical. The active ingredient in CheckMite+ is an organophosphate called coumaphos. Because this is toxic to both bees and humans, CheckMite+ should be used with great care.