Territorial Behavior in the Cicada Killer Wasp Sphecius Speciosus (Drury) (Hymenoptera: Sphecidae). I

Abstract

Male cicada killers (Sphecius speciosus) set up territories which are defended against intrusion by other males, other insects, and even thrown pebbles. Territory owners continually return to territorial perches, usually emergence holes. There is no apparent tendency for wasps to utilize their own holes of emergence as territorial perches. Aggressive flights by the owner terminate in one of four fashions, depending on the type of intruder and its behavior. Non-aggressive males and non-aggressive insects of other species are pursued without the owner getting within striking distance. Nonaggresive, slow-flying forms of other insect species are overtaken, and after an aggressive approach (here termed threat) the owner abruptly ends the chase. Non-aggressive male wasps or slow-flying insects of other species are butted by the owner. Grappling occurs with aggressive conspecific males and occasionally with non-aggressive conspecific males. Aggressive intrusion occurs when the intruder possesses an adjacent territory and first reacts to his neighbor while over his own territory. Most territories are set up in areas of high emergence hole density. Territorial behavior enhances mating efficiency by spacing the males and thereby increasing the frequency of male-female interaction. Localizing of territories in places of high emergence hole density fosters male-female interaction because the owners are more likely to contact emerging females. Mating efficiency is also probably enhanced by a reduction in the frequency of male-male interactions, thereby reducing the interference of superfluous males during precopulatory behavior.