They awaken each summer. From hidden burrows in the ground, they emerge to seek their prey. Each day the hunters tirelessly prowl their territories, pouncing without warning. They subdue each hapless victim before dragging them into dark tunnels, to feed the next generation…
Who are these mysterious creatures? They are the cicada killer wasps, and despite their fearsome appearance, they’re a true threat only to their prey, the cicadas.
Profile of a Cicada Killer
Eastern cicada killers (Sphecius speciosus) are large, solitary wasps that are native throughout the eastern portion of North and Central America. They range in size from just over half an inch to two inches in length, with females being larger than males. Their large size and striking, brownish-red, black and yellow coloration are reminiscent of giant European hornets, or of the “murder hornets” whose appearance in the Pacific Northwest made headlines last year. However, cicada killers are part of an entirely different family of wasps and bees. Further, as solitary wasps they are significantly less likely to sting – even in defense of their nests or territories.
Scary-looking, but Docile (to us)
Far from being dangerous to us, cicada killers are described by University of Kentucky entomologist Lee Townsend as “mild-mannered”. They are focused solely on their mission of establishing territory and securing food for their nests. Male wasps appear first in our yards and are very territorial, staking claim where females are likely to visit and pursuing anything that encroaches on their turf. Competing males grapple each other mid-flight as each strives to eject the other out of “his” airspace. Males will also “buzz” other insects, birds, vehicles, and humans that traverse their territory. This behavior can be alarming to us – however, male cicada killers don’t have stingers and thus are harmless. After a brief stare-down, the wasp will usually dismiss us and continue his patrol. While females have stingers, they are reluctant to use them on anything except their prey.
Did you know? Cicada killer adults don’t eat cicadas! Only larvae feed on the paralyzed insects – adults feed exclusively on nectar and plant sap. These insects provide both pest control and pollination services!
Each female wasp digs and provisions her own subterranean nest burrow, or gallery, which can extend between 30 and 70 inches long. The female lays an average of 15 eggs per burrow, each in its own side chamber located off of the main burrow tunnel. To ensure that each young wasp will have adequate food to support its growth, she stalks the surrounding trees for cicadas. She paralyzes each one with her sting and then drags the much-larger insect into her burrow. This National Geographic article explains the female wasp’s hunting process in fascinating detail. She will provide between one and three cicadas per egg chamber.
After hatching, the larvae feed on the paralyzed, but still living insects. Gruesome though this may seem, the wasps do contribute to the necessary control of cicada populations. After feeding, the larvae spin a cocoon and pupate, developing into their adult form in time to emerge the next summer. Cicada killers are most active in our area between mid-July and late August.
Despite the insect’s fearsome appearance and males’ territorial behavior, cicada killers are not dangerous to us. Female cicada killers sting only when handled roughly, and their sting is purportedly mild.
Female cicada killers typically burrow in soil that is loose and well-drained, with sparse vegetative cover. Their burrows can displace several pounds of earth, which is mounded around the outside of the tunnel entrance. Large aggregations of cicada killer burrows in one area can disrupt plant root systems and look unsightly. Entomologist Townsend advises wetting or disturbing the soil around burrows if they present an issue, as this tends to discourage burrowing activity. Replacing much of the lawn in your yard with thriving (and mostly native!) gardens that mimic native plant communities can also dissuade wasps from forming large collections of tunnels. I have noticed in my own yard that the wasps limit tunneling to sunny lawn areas (another argument in favor of reducing lawn area), and also tend to avoid areas compacted by frequent foot traffic.
Further, considering that these gentle giants are not a threat to us, perform a necessary ecological role, and in any case are active less than two months each year…why not consider letting them alone and enjoy watching their activities? Cicada killers offer a fascinating glimpse into the complex web of interactions between predator and prey. Their seasonal appearance marks the arrival of high summer for our region as surely as the buzzing song of their cicada prey or the nocturnal chorus of the katydid. And, once you understand that the territorial behavior of the male wasps is all bark, no bite, you may come to view their aerial antics with some humor. I have come to appreciate their presence in my yard, and hope that you will, too!