The Western Yellow Jacket

Community Contributed

By Glenn Teves, Extension Agent, UH CTAHR

Over 25 years ago, we encountered a swarm of some vicious Yellow Jackets at Forest Camp. Later, as we ate lunch of venison and rice, they started landing and feeding on the venison. I knew this wasn’t just any old Yellow Jacket; this was the notorious Western Yellow Jacket. Yellow Jackets are wasps, and have a predatory and also a scavenging habit and will feed on many insects, including plant-eating insects and nuisance flies around house and garden. However, they become a major threat when they attack humans, good insects and animals, including Hawaii’s native species.

Yellow Jackets are considered social insects due to their ability to live in harmony with other members of their species, and can also attack in groups, and have been in Hawaii for a long time. The Western Yellow Jacket is a more recent arrival and is believed to have arrived in shipments of Christmas trees. On Molokai, they’ve been around for over 25 years, but are recently making increased appearances in Ho`olehua. Although not a bee, they’ve been referred to as the “Meat Bee” due to their preference for meat or protein, and that means us.

The Western Yellow Jacket thrives in hot dry conditions, and is a brighter dark yellow, almost orangish color, compared to the common Yellow Jacket. They are ground dwellers, making nests in soil cracks or cavities in rocks, and are more aggressive and easily riled compared to the common Yellow Jacket. Any ground disturbance such as the thumping of feet or hooves will send them into attack mode in order to protect their nests. They’re a major concern on Hawaii Island in lava fields when disturbed, and have been known to attack and kill horses.

They search for meat or protein to feed their babies or larvae and can sting and bite repeatedly. In tropical areas they can survive for several years and nests can become quite large with over 1000 individuals. The most immediate solution when encountering them is to run. Multiple stings can increase the volume of foreign protein injected into your body, and if you’re especially allergic to them, it can be dangerous.

The longer the hot dry season, the more aggressive they get as populations increase and food supplies decrease. When food gets scarce they will start to singularly scavenge for food in garbage, or picnic areas. Once they find food, they will continue to return to the source. If you know where they are, try not to go near their nesting places; look for wasps flying in and out of a single location.

Wasp removal strategies or ways of minimizing them include the use of traps or lures. Trapping is one method that can be employed to try to reduce Yellow Jacket problems. They will eliminate individuals but probably not the entire nest or large populations. The active ingredient that attracts the Western Yellow Jacket is Heptyl Butyrate. Attracting them away from residents is important, so placing lure and traps along the perimeter of property in advised. Western Yellow Jackets are good flyers and can forage for a ¼ mile. Even when using long distance nest sprays, be ready to run because you don’t know how large the nests are. Using protective clothing to control them may decrease your chances of being stung, including bee harvesting equipment.