The Asian giant hornet may be all over the news, but residents of San Mateo County are far more likely to encounter our local species of bees and wasps. As the weather warms up, these insects become more active and more numerous in yards. Although capable of stinging, most species are non-aggressive, and only sting defensively when their nests are threatened.
Get to know your winged black-and-yellow neighbors!
Honey bee – Small, fuzzy, with tan-and-black stripes. Often carry pollen on their back legs. Builds wax combs in nests in tree holes or other natural cavities, or kept by beekeepers. Not aggressive. Important pollinators and producers of honey.
Bumble bee – Very robust and fuzzy. Size variable. Often have a yellow face and dark black body – or black with yellow stripes. Builds nests in the ground – usually in existing burrows or holes. Not aggressive. Important pollinators.
Carpenter bee – Largest bee in California (up to an inch long). Females are entirely black with a fuzzy round body. Males of the most common species (Valley carpenter bee) are a golden color. Bores its way into wood (usually dead branches or untreated deck wood). Nests as a small group or a few individuals tending a brood. Not aggressive. Important pollinators.
Yellowjacket –Black and yellow, similar in size to a honey bee. Builds large hives in trees or underground with hundreds to thousands of individuals. Predator of garden pests (caterpillars, leaf hoppers, aphids etc.). Can be aggressive if you approach the nest. The District offers ground-nesting yellow jacket control services.
Paper wasp – Black and yellow with a skinny waist and long spindly legs. Builds nests with open combs near the eaves of buildings. Not aggressive, but will defend their nest. Predators of garden pests.
Mud dauber – Black and yellow or metallic blue-black with an extremely skinny long waist. Builds nests out of mud on the side of buildings. Predator of other insects – especially spiders (including black widows). Not aggressive.
If you’re worried about murder hornets – fear not! They’re not in California.
Asian giant hornets (Vespa mandarinia) aren’t in California, and there is no current evidence they are headed this way. In fact, they have a somewhat overlooked history of averted introductions into North America. As recounted in a recent article in the online journal Science News, V. mandarinia was previously detected in 2016 by a USDA inspector in Sacramento. A shipment containing an entire nest of live larval and pupal hornets was intercepted at the San Francisco airport. The nest had likely arrived from Asia, where these insects are sometimes harvested as ingredients for food or drink.
It can be difficult for people who aren’t entomologists to understand how different these insects are from local wasp species, so we put together a helpful graphic so you can see how none of our native bees and wasps look like giant hornets. Please feel confident that wasps and bees (including giant hornets) have no interest in hurting you. If they sting, it is always in defense – of themselves or their hive. Most bees and wasps will even warn you when they are considering stinging – through clicking noises, high pitched whining, or flying in specific patterns. Paying attention to these cues, freezing until you can figure out where the wasp or bee is, and backing away from them, is the safest way to avoid being stung. If you are sensitive to bee venom, make sure you discuss with your doctor and carry antihistamines or an epi-pen whenever you are outdoors.