Dealing with a bee infestation can be tricky and even dangerous at times. However, unlike the popular honey bee or often feared killer bee, the bee that is actually the most common on nearly every continent (except Australia) is the sweat bee. Named because they are often attracted to the salt in human perspiration, sweat bees aren’t as aggressive or dangerous as other stinging bees and are relatively simple to get rid of.
Step 1 – Identify the Bees
Sweat bees are small insects from the Halictidae family, ranging from 3-10 mm in size. Despite being very common, the reason they are often overlooked or misidentified is because don't have the yellow coloring commonly associated with bees. While some sweat bees can be yellowish, many are a metallic black or green color. Because of there different coloring and the fact that they are more likely to get up close and personal, especially when you’re sweating outside, many people confuse them with common flies or other insects.
While not as prevalent as the honeybee, entomologists have identified sweat bees as playing a role in plant pollination. As such, your first instinct should be to seek the services of a local beekeeper. This way the bees can be relocated, thus solving your problem without killing the bees and negatively impacting the ecosystem.
However, if extermination is your only option or preferred method, follow these additional instructions.
Step 2 – Locate Nesting Sites
Once you’ve confirmed that you do indeed have a sweat bee problem, you need to locate their nesting sites. Unlike other bees, sweat bees do not have one common hive and tend to build multiple smaller nests in close proximity to each other that may or may not connect.
Sweat bee nests are often found underground, in tree or wood cavities, or in shrubbery roots.
Again, this variety of bee isn’t aggressive and will only sting if directly swatted or provoked. So, you should have a fair amount of time and peace to observe the habits of these pests and follow them back to their homes.
Step 3 – Mark the Nests
The best time to kill the maximum number of bees is during the night when they are all gathered in their nests to sleep.
Because their nests are so small and often covered, you should use small garden markers such as flags or sticks to denote where each nest entrance is in your yard while it is still light out. This will make things much faster when you’re moving around in the dark evening hours.
Step 4 – Pick Your Poison
Now that you know where to strike, decide on your method. Popular commercial insecticides include carbaryl, commonly sold as a powder, and malthion, sometimes called maldison.
Carbaryl is highly effective but is also toxic to humans and has been shown to be cancer causing. Malthion is very low in human toxicity, but is lethal to aquatic and amphibious life. This is something to keep in mind if your yard has any ponds or fish. Crustaceans are particularly vulnerable to this pesticide.
WARNING: Other sources may suggest the use of a third insecticide, diazinon, but be aware that this information is likely outdated. Diazinon has been illegal for residential use in the United States since 2004 and can only be purchased for agricultural purposes. This means that it is still on the market. If someone sells it you and you use it in your home, you are still the one breaking a law.
Step 5 – Wear Protective Clothing
Although gentler than other bees, these insects are still bees, and they do have stingers. This method of extermination does require you to get close to their nests and apply a physical insecticide that may agitate them enough to swarm at you.
Wear long pants tucked into your socks, long sleeve shirts, and eye protection. Cover as much exposed skin as possible to reduce the chances of being stung.
Step 6 – Spread the Insecticide
Be sure to follow any manufacturer instructions for residential use, and mix your insecticide in the proper quantity and transfer it to an appropriate delivery vessel.
Approach the nest entrances and spray or sprinkle the area generously. If you are using malthion and have chosen to dilute it in a solution of mostly water, you may need to make multiple applications over multiple days to see results.
Ideally your application will cause any sweat bees that exit the nest to collect nectar or pollen to track the poison back into the nest when they return, killing the whole colony.
Step 7 – Observe Your Results
Over the next week, keep track of whether the amount of sweat bees you’re seeing drops at all. If you see continual sweat bee activity, you should wait for night to fall and repeat your application process. Depending on which insecticide you are using and how large your infestation is, you may need to reapply the poison three to five times.
Step 8 – Prevention
If you feel confident that the sweat bees in question were a one-time invader, you’re done. However, if you are worried about more sweat bees returning in the future, add large amounts of compost or peat moss to the areas where the nesting sites once were.
Additionally, planting a ground cover like ivy will also make the area less desirable for sweat bees looking for a nesting spot.
Outside of the home, the people most often plagued by sweat bees are outdoor laborers, such as gardeners, construction workers, and road workers because of their exposed perspiring skin. These are bugs attracted to sweat.
Because their work sites often vary from day to day and it is unlikely that these workers have to time or ability to stalk around at night looking for nests, the options for true relief here are limited.
However, assuming that you're working in an area away from aquatic life and that your employer and fellow employees do not object to it, spraying a diluted solution of water and malthion in the area may help. Just keep in mind that while malthion does have a very low toxicity, it is dangerous if ingested or inhaled directly. If you want to attempt this solution, make sure you are spraying the ground or objects around your work site. Do not apply it topically to the skin or in a way that promotes inhalation of the chemical.