High numbers of Western Yellowjacket wasps are currently occurring at Haleakalā National Park. Yellowjacket numbers typically increase during the late summer and persist through October. Resource managers are actively controlling yellowjackets in heavily visited areas. However, wasps are still swarming.
Areas where yellowjacket numbers are extremely high are at the base of Sliding Sands trail where the horse tours normally stop, and at Kapalaoa Cabin. Yellowjackets are also present at lower levels at other locations within the park.
Yellowjackets are aggressive and may sting without warning. They are attracted to water, meat, sweets (both food and drink) and sweet-smelling perfume, cologne, and sunscreen. They may swarm around people who stop for a snack or meal. Unlike bees that sting once and die, yellowjackets sting repeatedly. Do not swat at these wasps as this will only make them more aggressive. If wasps are swarming around you, put away any food or drink and walk calmly away from the swarm.
Yellowjacket stings can be very painful to people, and may cause anaphylactic shock in some individuals. Visitors who are allergic to wasp or bee stings are asked to carry necessary medications and consider not visiting problem areas. If a serious reaction occurs, call 911 and go immediately to the nearest medical emergency facility.
Yellowjackets are an introduced species that established on Maui during the 1970’s. In addition to being a human pest, the yellowjackets are a threat to native Hawaiian ecosystems by preying on native insects.