Unusually High Number of Horseflies (Tabanidae) and Wasps (Vespula)

Observation by Rebecca Charles:

We have an unusual high amount of horseflies/wasps that are in town, just about every household has some around their homes.

Derek Sikes, Entomologist at the University of Alaska Fairbanks Museum of the North, writes:

I don't know what factors favor horseflies, sorry. Yellow jackets often become more common and bothersome near the end of the summer. Their populations are at their highest point then before the frosts kill them off (except the new queens which overwinter under the leaf litter). Dry conditions in the spring are thought to increase yellow jacket survival. Once they have their nests & worker force established, the dryness or wetness of the weather is probably less important.

Comments from LEO Editors:

Many areas in Alaska have experienced unusually warm temperatures this year, but Nome experienced both warm temperatures and higher precipitation than normal. Pictured below are three maps that show the temperature and precipitation departure from normal during the spring season, represented by a snapshot in March, and during the summer represented by a snapshot in July. Erica Lujan

Horseflies are found in much of Alaska and around the world. They like sunlight, so sunny weather could explain their surge in activity. They are not active (thankfully) in the dark of night. The females will bite animals to get blood for producing eggs. Like mosquitoes they are attracted to animals by our breathing and specifically carbon dioxide. The bites are generally not harmful for people, but should be cleaned and can be treated with an over=the=counter disinfectant like Neosporin. See article at Healthline.com. More often, the bites are associated with illness in horses, such as equine infectious anemia. Horseflies globally have also been known to carry parasites, anthrax, and tularemia. The health risks as far as painful stings and allergic reaction with wasps are well known, and in recent years there have been more wasps, wasp stings, and hospital visits. This has been linked to climate change as an emerging health threat. See article by Demain et.al. Increasing Insect Reactions in Alaska: Is this Related to Changing Climate? and attached document by Yoder and McLaughlin on potential health risks of climate change in Alaska. Mike Brubaker