August 15, 2017
What do you love most about summers in L.A.: picnics on the beach, Griffith Park barbecues, camping in the mountains, eating hot dogs at a Dodger game? I love summers for those reasons, too, but it is also my favorite time of the year to look for insects, a lifelong obsession I can’t seem to shake. Most bugs are busy doing whatever they need to do to survive without any trouble to us humans, but sometimes uninvited insect guests show up to our summertime celebrations and help themselves to our burgers and carnitas tacos.
The biggest culprits are wasps that naturalists call yellow jackets, although I have heard people refer to them as “meat bees,” (as well as some other names I cannot mention in polite company). Yellow jackets are indeed a huge nuisance at barbecues and birthday parties; they come very boldly in large numbers to bite off pieces of meat. If a person gets in their way, they can produce a painful sting, about the same strength as a honeybee sting, but unlike honeybees, yellow jackets can sting repeatedly.
I have become so accustomed to seeing them eat “people food” that I was intrigued when I recently saw a photo on iNaturalist of yellow jackets systematically eating a Southern Pacific rattlesnake down to the bone. Yellow jackets are opportunistic predators that usually hunt spiders, and other insects like caterpillars, but they will also scavenge protein where they can find it. Whether that is a dead cow in our burger, or a dead rattlesnake on the ground, meat is not to be passed up as it is essential for the survival of their colony.
Like some other species of bees, wasps, and the majority of ants, yellow jackets have a queen. The yellow jacket queen emerges in the spring, constructs the nest from wood fibers, lays her eggs, and begins to hunt for insects and spiders to feed her offspring as soon as they hatch. Once her infertile daughters are fully grown, they will carry on as workers by providing protein sources to their younger sisters while their queen stays in the nest to lay more eggs. Males are around only in late summer to mate with potential future queens, who will start new colonies the following spring. This means that the yellow jackets you see hunting in your gardens, scavenging carrion on trails, or helping themselves to your barbecue are females that are working hard to feed their little sisters.
In the process of collecting food, yellow jackets help to keep insect populations in check, acting as what gardeners call “beneficial predators,” but they also play an important role as part of the clean-up crew of the natural world. Along with some species of beetles and flies, yellow jackets are helping to recycle nutrients by scavenging dead animals. They are even important to forensic entomologists, scientists who analyze crime scenes by studying the insects that visit corpses. Carrion feeding insects only feed on dead animals at certain stages of decompostion, so identifying the insects can serve as a clock for investigators to approximate when death occured. In studies conducted with pigs to understand the role wasps like yellow jackets play in breaking down decaying animals, researchers observed wasps clipping pieces off of pig’s ears. No wonder yellow jackets are lured in by the smell of cooked hot dogs, pig parts rolled up in a tasty, easy to bite off bundle! As predators and scavengers, yellow jackets are willing to eat a wide variety of meat, not unlike some humans. Maybe this common ground will help us to make peace with these uninvited summertime guests.
“Yellow jackets and Paper Wasps.” Landolt, Peter J. and Arthur L. Antonelli.
“Occurrence of Hymenoptera on Sus scrofa carcasses during summer and winter seasons in southeastern Brazil.” Gomes, Leonardo et al.
Special thanks to Patrick Gavit and Gary Woo for their amazing photo submissions, and to Dr. Greg Pauly who shared them with me!