In recent years these large, boldly coloured wasps have taken up residence in High Park’s sandy soil. Despite their imposing size, they are not a threat to people. Males constantly patrol their underground nesting sites and may aggressively fly right up to people in defense of their nest even though they cannot sting. Females have a weak stinger that can’t do any significant harm to people but works well on their target prey: cicadas.
Here is an excerpt from Underground Creatures of High Park, by Kathleen Keefe (part of her High Park A to Z series).
Cicada-killer Wasp
When the female of this imposing species is on the lookout for a good nest site, she seeks light, well-drained, sandy soil in full sun near trees that host cicadas. She digs a 1.5 cm wide tunnel down through the soil to a depth of 30 to 40 cm and then tunnels horizontally for a metre or more. To excavate, she uses her jaws to remove soil and her spiny back legs to push it out. She removes enough soil to fill a shoebox! Along the tunnel, she builds a dozen or more egg-shaped side chambers, furnishing each with one to three cicadas she has paralyzed with her venom. She then lays an egg on each cicada and seals the chamber with soil.
This keeps her busy for several weeks from July’s end to the beginning of September. By day, she stays in the tunnel and by night, she flies around preying on cicadas. The grub-like wasp larvae hatch in two or three days and for the next ten days, they feed on the paralyzed cicadas mom provided. If the nest survives, each larva spins a silken case in the fall, and prepares to overwinter. Threats to the nest include marauding skunks that devour both the cicadas and the wasp larvae.
