Small Hive Beetle (Aethina tumida)
By Education Specialist
What the heck are these things?
Some beekeepers who are not familiar with the Small Hive Beetle, henceforth called SHB, may wonder what these small brownish black beetles are running around in their hives. Let me tell you they can be real trouble. These pests are not native to the US but have now established permanent residence. They are here to stay and we need to learn how to deal with them.
Originating in sub-Saharan Africa this beetle is considered a minor pest in that region. Africanized honey bees have evolved to be able to deal with these pests as they have been pressured by them for a long period of time. It is thought that the Africanized honeybee has a stronger mandible and is able to bite and damage the beetle. European honeybees do not have this ability. First discovered in the US in 1996 in Charleston, SC, probably coming from Africa with a load of fruit, the SHB have now spread to almost all states to some degree. They seem to thrive better in warmer climates that have milder winters, but they can and will winter over with colonies in the north. While they cannot handle the cold, the warmth of the winter hive provides them protection.
What They Do
SHB are attracted to the smell of wax, honey, pollen and to some degree the smell of alarm pheromone being emitted by stressed bee colonies. SHB fly and are able to spread by this means. The guard bees of a colony will challenge these beetles as they try to gain entry to the hive but sometimes the number of beetles trying to get in will be so great as to let some of them slip by.
The female SHB will lay eggs in the cracks and crevices within a hive that the bees can’t reach and sometimes slit the caps on developing brood and deposit their eggs here. The female SHB can lay up to 1,000 eggs. As the eggs hatch the larvae will feed on the brood, honey and wax within the colony, tunneling through the comb as they go.
As they feed they defecate, causing the honey and nectar to ferment and ooze from the frames. This is called being slimed and is really an unpleasant situation for the bees to deal with. The honey will discolor and take on the smell of decay.
The larvae, having grown by feeding in the hive, will now migrate to the hive entrance and drop to the ground to pupate in the soil. Most SHB larvae will burrow into the ground within a foot of the hive if the soil conditions are correct. They prefer sandy soils to compact soil and will scurry some distance to find the correct conditions.
The adult SHB will emerge in about 3-4 weeks to seek out hives and mate. The female will begin to lay eggs in about a week, with the eggs hatching in 2-3 days and the life cycle repeats. Depending on your weather conditions, number of colonies and the feeding and reproducing opportunities, you may have 3-5 generations per year of the SHB. Remember that they can and will overwinter with the colonies. Adult SHB can live for up to six months.
As in most pest situations the first line of defense is to maintain strong colonies. If you have weak colonies you will need to keep an especially close eye on them for infestation. Keep your entrances reduced on weaker colonies so the bees are better able to defend them and consider combining hopelessly weak colonies with strong ones, as long as it is not a disease or infestation that has caused this weakened condition.
Avoid opening your hives more than necessary for inspections. One of the things the bees will do is corral the SHB adults into tight spots and propolize them in. When we go into the hives we may free many of these trapped beetles.
By keeping our hives in direct sunlight we may also reduce the number of SHB. They do not like direct sunlight and this may help tip the odds in our favor. Remember to allow your hives to vent in some fashion to let the bees maintain preferred temperatures.
Another consideration would be a ground treatment around our hives to kill pupating larvae. GardStar® is a commonly used insecticide which contains a percentage of Permethrin. This is applied with a watering can around the hives with care to not let it come in contact with the hive itself. Depending on rainfall this will need to be reapplied occasionally. I have also heard of people using diatomaceous earth around their hives and in some bottom-mounted SHB traps. This earth has ground-up marine life in it and the larvae are cut as they crawl through it, causing them to bleed out.
Beneficial nematodes are another option. They are mixed with water and introduced to the soil around the hives, where they seek and destroy pest larvae.
After experiencing terrible losses in south Mississippi last year to SHB I have found some benefits to using salt in various ways. Purchasing the mineralized salt sold by the farm stores (used as a mix with animal feed) I will combine roughly 3/4 of a pound with two gallons of water in a weed sprayer. I will spray this mixture around my hives to kill pupating larvae in the ground and to act as a weed control. Remember after use to clean your sprayer with water to prevent corrosion of any metal parts.
In the case of using solid bottom boards you can also cover the bottom boards with salt. This is detrimental to any larvae crawling through it as the salt will desiccate them. Avoid getting salt on any frames as this can be lethal to the larvae of bees as well. If using a screened bottom board you may be able to remove the screen and move your debris board up into its position and salt that. While I have heard some experienced beekeepers say that bees do not need or seek salt, I beg to differ; I constantly have bees on me licking the salt off my arms. In addition I have a swimming pool and live on a small lake and the bees use both. I am convinced it is the salt that they are seeking.
I have also set up a bird bath in which I mix three teaspoons of salt to a gallon of water and provide it to my bees. This may also help to keep them out of your or your neighbor’s pools. If your neighbors are not beekeepers this can become a real problem. One of the things you may suggest to them is hanging a towel over the edge of the pool to try to attract the bees to using only one area.
There are many beetle traps on the market today. Some fit in between the top bars of your frames, some are bottom mounted, some may trap the beetles as they try to enter and some may be homemade from CD cases or the like. Some use both an attractant and a killing agent once the SHB is inside, such as poison, oil to suffocate, or diatomaceous earth to cut them.
I encourage you to research these traps to find out what is legal and which ones work best. Some researchers are working on traps and pheromones that will draw the beetles and contain them prior to them entering the hives. While I hope this works I can’t help thinking of the time I put up Japanese beetle traps around my property. It seems that you want to put these traps on your neighbor’s property instead as they seem to draw every beetle in the county.
When I am opening my hives for inspection sometimes I will see SHB running around on the top bars. This is where I take some satisfaction in killing as many as I can with my hive tool. While this is not the most effective means it does give me pleasure. You may also want to overturn your outer cover and set your top box on it. As the beetles run from light they migrate down onto the overturned outer cover providing more squishing opportunities.
When you remove your supers for harvesting it is important that you get them extracted as quickly as possible or the hive beetles may have a field day in your honey house if you don’t. We like to freeze our frames immediately after harvest to kill any eggs that may have been deposited by the SHB—24 hours should be enough. If you’re not returning the supers to the hives, be sure to tightly seal them to protect them from SHB even after freezing.
What To Do If I’m Overrun
Sometimes things will get away from us and we will open a hive and see the devastating effects of a SHB invasion. While we still have bees and a queen it is obvious that if something is not done we will lose the colony. I would immediately transfer any unaffected frames and bees into clean equipment. Kill as many SHB as you can, as you go. Take affected frames and freeze them. Only give the bees as much room as they can defend. Either move the hives to treated ground, or treat the ground they are on. Reduce your entrances as this will help the bees to defend. Remove any pollen substitute from the hive as this can be a magnet for SHB.
Employ any or all of the above mentioned remedies I have described. Take your old boxes and bottom boards and clean them up well, scraping out the slime and washing with a bleach solution and salting them when dry. Monitor this hive closely and feed if necessary.
While there does not seem to be a magic bullet for SHB, I believe by using the above methods you can minimize the damage caused by the little buggers. By using multi-pronged approaches we can certainly go a long way to helping our bees defend against them.
Perhaps our bees, after being pressured by these pests for a while, will develop better ways of dealing with them. I know I have witnessed hives that seem more predisposed to dealing with them and the genetics of hygienic behavior may have something to do with this. One other interesting and disturbing fact of the SHB is that they have learned how to beg like a drone and in some cases the bees will feed them!