Small Hive Beetles (SHB)
Jerry Hayes
More info than you really need.
One of the challenges in being a beekeeper with decades of KSA’s, Knowledge, Skills and Abilities (or simply Old) is that we have lots of confirmed data and lots of real-life experiences. Here is some information that hopefully makes sense in your contemporary journey with SHB.
Insecta: Coleoptera (beetle) Family: Nitidulidae (sap) Aethina tumida i.e., the Small Hive Beetle. The SHB is a native of Sub-Saharan Africa. The Nitidulids (or sap beetles), such as the familiar picnic beetle feed on plant fluids/saps, fermenting fruits, fungi etc., but SHB also need high protein diets when they are trying to reproduce. They scavenge on feral African Bee colonies, which are a tropical/sub-tropical insect that doesn’t have to stay in one location, always preparing for the next winter, unlike our European Honey Bees have had to do for the last 400 years-to genetically adapt to living through long, cold, hard Northern European Winters. African honey bees can ‘abscond’ i.e. the whole colony leaves a hive location to escape predators and pathogens in the comb, or look for more flower resources. Absconding is not ‘reproductive’ swarming where part of the colony leaves to spread its genetics around in a new area and the other part of the colony stays behind in the original hive location. African Honey Bees can abscond dozens of times per year because survival is not totally dependent on honey stores.
SHB have made some amazing adaptations to take advantage of feral honey bee colonies in Africa that have of course, been transferred to the U.S. While African honey bees abscond due to constant predation from humans, honey badgers or other pests, SHB can continue to reproduce for a while, on the abandoned comb. SHBs can also force the issue, because they can produce a similar queen-like pheromone that can cause the Queen to slow egg production. As the colony population drops to the point that the bees can no longer protect their colony, the SHB move in and become active predators resulting in the African Bee colony absconding.
The first reported sighting of SHB in North America happened in 1996 when a beekeeper in South Carolina noticed several small black beetles in a colony established from a recent swarm. The beekeeper collected samples of these beetles he had never seen before and sent them to Clemson Univ. for ID. An insect taxonomist tried to ID them but did not have enough of the ‘keys’ needed to identify the genus or species. In 1998 an apiary in Florida was destroyed by beetles that were properly ID’d as SHBs. The adult SHBs collected two years earlier in South Carolina were then ID’d as Aethina tumida, SHB.
How SHBs were introduced into the U.S. is still unknown but global travel and trade has resulted in items being moved around and shared regularly.
Having been the Chief of the Apiary Section for the Florida Dept. of Agriculture and Consumer Services in the ealy 2000’s I heard lots of early SHB stories from my predecessor, Mr. Laurence Cutts. Mr. Cutts told me that since SHBs were native to Africa, he invited a group of South African Commercial Beekeepers to come to Florida see what challenges Florida beekeepers were having and ask for their advice. A small group came and toured the State looking at management techniques, SHB impact and assessing the situation. After touring and talking to beekeepers for about a week, Mr Cutts asked the South African Beekeepers for comments and recommendations. Remember that the South African beekeepers had been managing SHB issues for decades and had a plan. When asked, the South African beekeeper entourage said, “you Florida beekeepers are the sloppiest, nastiest beekeepers we have ever seen!” The South African beekeepers would collect honey supers and extract within 48 hours and then put the supers back on the colonies for cleanup. Florida commercial beekeepers would collect supers, stack them in their warehouse next to the extracting room and extract as soon as they could, days or weeks later. This is a great opportunity for SHBs to start feeding without interruption by the colony. Some of the commercial warehouses had two to three inches of SHB larvae as well as the ‘slime’ associated by the beetles, produced by the yeast Kodamaea ohmeri on the floor. The employees were walking through this mess! South African beekeepers were not impressed.
SHB are looking for a safe, warm place that has lots of positive resources to reproduce like other organisms. Their Nitidulidae cousins must find some rotting fruit, sugary sap, or fermenting melons and maybe some pollen for protein so they can reproduce and lay healthy eggs. SHBs adapted so that they can obtain all their nutrients from honey bee colonies – honey for concentrated energy, pollen for protein, a dark, warm site for SHB larvae to develop, soft squishy honey bee eggs and larvae, plus royal jelly, making the bees’ home a buffet smorgasbord of resources. So, SHBs adapted, and with their roundish, smooth, tank-like bodies that are hard for bees to grab and manipulate, developed a relationship with honey bee colonies first from Africa to now on several continents. This survival adaptive lifestyle became successful.
This is what we have learned approaching 30 years with this new honey bee colony predator.
SHBs are adapted to seek out honey bee colonies that are declining in health, vigor, and population. If a honey bee colony is weakening because of poor beekeeper monitoring and safe, efficacious control of our biggest honey bee health concern- Varroa destructor and the Varroa/Virus Legacy, the colony is a prime location for SHBs to reproduce. When a honey bee colony is sick for any of a variety of reasons, it is stressed and produces stress pheromone odors. SHBs have sensitive club-like antenna that can pick up those stress pheromones several miles away and follow them to the apiary or directly to the colony. They, meaning sometimes hundreds of SHB who independently picked up the weakening colony(ies) stress odor, will select a colony to wait in until the colony(ies) have weakened even more, then immediately begin laying eggs. Some may have already entered the weakening colony(ies), and other than the bees harassing them, are not in any danger. If they have been in the colony for several days, they also can pick up colony odors and have bees in the colony think they are one of them and feed them via trophallaxis. Sometimes if the colony is still strong enough, it can herd some SHBs and corral them in an area with a propolis wall around it. But this is only temporary.
When the SHB females begin to lay eggs, they can deposit hundreds in and around capped brood or beebread. Depending on hive temperature and humidity, an egg hatches after one to four to five days. When it hatches, the SHB larvae look different than the plump, fleshy Wax Moth larvae that you may have seen. SHB larvae are thinner with a tough cuticle and have three pairs of short strong legs at the front of the body. Wax moth larvae have the three pairs of true legs at the front of their body and four pairs of fleshy legs toward the back of their body called prolegs.
The SHB larvae are devious at seeking and finding food in the colony. This food is brood, which is high in nutrition, beebread, and honey. The SHB larvae obtain nutrition with the help of the yeast Kodamaea ohmeri which has a symbiotic relationship with the adult SHB- they work together. When Kodamaea is introduced to a colony, it starts feeding on honey and other resources and produces a thick slimy goo that helps it spread and pre-digest food for itself as well as a deterrent to honey bees trying to live in the colony. Kodamaea also produces an odor that attracts SHB outside of the colony as well. This is where our European genetically based honey bees are at a loss. African bees in this situation would have left that location long ago but, our European bees will hunker down and die in place or rarely leave as the SHB and slime displace them, driving them out of the hive. In seven to 10 days, the SHB larvae mature, then crawl out of the colony and drop to the ground. If the ground below the hive is moist enough, they may burrow down several inches to several feet to pupate into an adult SHB that emerges, and the life cycle begins again. If the soil is dry and not conducive to burrowing into the soil, the SHB larvae will crawl hundreds of yards to find a location along a tree line or field setting that is more favorable.
If your colony has become a SHB nursery and it is slimed and larvae are emerging, it may be too late to save it. You didn’t manage, inspect regularly, sample and treat for Varroa and waited too long to correct the problem. That colony is now repellent to honey bees and basically unusable to them….and you.
In the Southern U.S., SHB adults can overwinter in the environment or inside a hive that is weakening. Here in the north, they overwinter inside the colony, specifically inside the cluster here it is warm and safe. Remember they can ‘trick’ the colony that they are one of them. And then in the spring they can assess whether that colony or others in the area are potential reproductive possibilities.
A variety of traps and chemical control measures are available to manage SHB. Having less SHBs in your colony is better than more. But…. if your colony is attracting SHBs what does that tell you about the colony health and your management of it?
