The eastern cicada killer, Sphecius speciosus, is a solitary wasp, with females often measuring up to two inches long. Despite their alarming appearance, these wasps are non-aggressive and do not form the large, defensive colonies associated with hornets or yellowjackets. The presence of this giant digger wasp is a direct result of specific environmental and biological conditions it seeks out, including the availability of prey, suitable soil, and adult food sources.
The Availability of Cicada Prey
The primary biological driver for the presence of the cicada killer is the availability of its namesake prey. Female wasps are instinctively attracted to areas where annual cicadas are abundant, as the cicada is the sole food source for the developing larvae. The female hunts by paralyzing the cicada with a sting, ensuring the prey remains alive but immobile to preserve a fresh meal for the offspring.
Once paralyzed, the female drags the cicada back to her underground burrow. This hunting behavior dictates that the wasps will congregate near mature trees, such as oaks and maples, where cicadas feed and are most easily found. The density of the local cicada population directly correlates with the attractiveness of a yard for a female looking to provision her dozens of nest cells.
Specific Ground Conditions for Nesting
Nesting is heavily dependent on specific soil characteristics. Female cicada killers are digger wasps that require loose, well-drained soil for constructing their burrows. Ideal nesting material includes light, sandy, or loamy soil that is easy to excavate.
Nesting sites are almost always in full sun exposure, which helps keep the ground warm and dry. The wasps avoid damp, compacted, or heavily shaded areas, making dry patches of lawn or sparsely vegetated slopes highly desirable. Females often burrow along the edges of sidewalks, patios, or in flower beds, where the soil is typically bare and easily disturbed.
A single female can move a significant amount of dirt, often creating a horseshoe-shaped mound of excavated soil around the entrance hole. Favorable soil conditions can lead to several females nesting in close proximity, creating an aggregation of burrows. Homeowners can inadvertently encourage nesting by having thin patches of turf or exposed soil, as a dense, well-maintained lawn is much harder for the wasp to penetrate.
Food Sources for Adult Wasps
While the larvae feed exclusively on paralyzed cicadas, adult cicada killer wasps are nectarivores. This dietary need is a secondary, but significant, factor in attracting the wasps to a yard.
The adults seek out flower nectar, which they consume while also acting as accidental pollinators. Landscaping that includes nectar-rich flowering plants can inadvertently draw the wasps into the area. Other sources of simple sugars, such as fermented tree sap or honeydew excreted by plant-feeding insects like aphids, also serve as attractive food sources. These sugar sources provide the necessary fuel for the adults to maintain their brief life cycle of hunting and nesting.