Pompilidae: Spider Wasps

Biology

Spider wasps are a very diverse family with 300 species in North America. As their name suggests, they specialize in hunting for spiders and rarely feed on other prey.  Spider wasp nests are usually shallow burrows provisioned with a single spider.  Unlike some other wasps, Spider wasps capture their prey and subdue it before excavating a nest.  The moribund spider is usually propped up nearby, while the wasp is busy excavating.  Typically, a single egg is laid on the abdomen of the spider, and the nest or burrow is closed so the larva can develop without disruption.  The egg hatches and the larva feeds on the spider.  As the larva feeds, it saves the vital organs, such as the heart and central nervous system, for last.  When mature, the larva spins a durable silk cocoon, and emerges as an adult either later in the same season or it overwinters.  Spider wasps characteristically flick their wings nervously, while hunting on the ground.  Both sexes visit flowers frequently, preferring open disk-type blooms with shallow nectaries.