Small Hive Beetle (Aethina tumida) Now in Michigan!
Entomology, MSU
10/26/1999
The small hive beetle, Aethina tumida Murray, is a new pest attacking honey bees and hives in US. Its native range is sub-Saharan Africa; where it is considered minor in its effects, attacking weakened colonies and combs in storage and treatment is seldom necessary. In the following I will discuss briefly its morphology, distribution, biology and control.
1. Classification and morphology: This critter is a member of the beetle family Nitidulidae, which are mostly scavengers (such as sap beetles, strawberry beetles). Adult beetles are about 5-7 mm long, dark brown to nearly black, with clubbed antennae. Move fast and play dead when touched. Larvae are white grubs that can be easily confused with waxmoth larvae, but they move differently (waxmoth larvae tend to undulate while beetle larvae do not). Pictures of both are available at: http://www.cyberbee.net/new-pest.shtml.
2. Distribution: SHB is first reported in May 1998 in Florida. It had been in South Carolina for at least a few years before its official discovery. It probably came with bees from a ship from South Africa. Right now it is established in Florida, South and North Carolina, Georgia and Ohio. It has been reported in Minnesota, Wisconsin, Michigan but probably not established yet in these States yet. In Michigan, the beetles seem to be mostly confined to a honeyhouse in SW Michigan. No larvae or adults were found in the 10 apiaries when I checked with a beekeeper during September. Updated distribution map is available at http://ceris.purdue.edu/napis/pests/shb/imap/shball.html.
3. Biology. Adult beetles find honey bee colonies (probably by smell), invade, and lay eggs inside. Both larvae and adults feed on brood, pollen, wax, honey, and damage brood and honeycomb. Larvae would leave slime and bad odor behind so bees would simply abandon the comb or the entire colony. Mature larvae are attracted to light and enter soil to pupate. The duration from egg to adult is abut 38-81 days in Africa and probably similar in Florida. Adults can fly upto 15 miles to find a colony. They can live for about 6 months. It has been shown that they can complete development (egg to adult) on rotten fruits such as cantaloupe and strawberry. Larvae must enter the soil to pupate. Adults emerge and fly to a colony of bees where it takes up residence.
4. Control. The most critical thing is early detection. Check your colonies carefully when you are working with them, pay special attention to top inner cover and bottom board for beetles. Collect them and send them to me (517-353-8136) or Mike Hansen (616-428 2575) for identification. Once positively identified, you can purchase CheckMite+ (also called Bayer Bee Strips, active ingredient is coumophos) from Mann Lake Ltd (1-800-233-6663 ). Michigan has obtained a section 18 (emergency registration) for the use of this pesticide, thanks for the effort by MDA. To use the CheckMite+ strips, prepare a piece of corrugated cardboard (4x4") and remove the cover of one side to expose the corrugation. Cut a strip in two and staple them to the exposed side of the cardboard and place it near the center of the broom board with the strips down. SHB are attracted to the cardboard as a hiding place and are then killed by contact with the coumophos strip. Treat for 3 - 45 days. It is not recommended to treat more than 4 times per year to prevent resistance from building up. This method probably works only when beetles just recently invaded the colony and have not started laying yet. Larvae would remain in the frames, and not have a chance to reach the cardboard trap, and would not be killed.
Soil treatment would complement the above method since larvae will be killed when trying to enter soil to pupate. GardStar (contains 40% permethrin) can be used for SHB and is available from Blossomland Supply (616-473-3917) or other stores selling cattle pesticides. Use 5 ml of GardStar per liter (0.05% active ingredient) and spray the area underneath the hive and at least 1 ft in the periphery of each direction. If you bring bees from the states where the beetles have established, you should treat the soil before placing the colonies. It is not clear how long the pesticide would stay active in the soil before re-applying is needed.
Right now most damages seem to be in the honeyhouses. We can no longer let honey supers stay for a month before extracting if we have beetles. Extract promptly (within one week), keep the honey house clean, and fumigate the extracted supers before storage or putting them back to the colonies.
6. Outlook for Michigan: It is difficult to say how soon (or ever) if the beetles will be established in the state. Once established it will require constant treatment for its control and increase the cost of honey production and pollination. It is clear that the beetle will be able to winter here, mostly inside beehives, based on the fact that it did so in Minnesota. They will not survive the winter in unheated honey houses or outside a beehive. At this stage we can eradicate it easily (before its widespread) if beekeepers bringing bees from other states take special precautions and always treat the soil before placing hives. Due to colder weather, it should be slower to be spread out here than in Florida. In addition we do not have as many decaying fruits and vegetable as in Florida to provide alternative breeding grounds for them.
The bottom line is: we have one more pest to deal with and they might be here to stay, and we need everybody to pay special attention to this new pest and hope they do not get established right away.