The behavior of nose bot flies (Cephenemyia apicata and C. jellisoni) when attacking black-tailed deer (Odocoileus hemionus columbianus) and the resulting reactions of the deer

Abstract

Larviposition behavior by Cephenemyia jellisoni involved a covert, inaudible hovering–"stalking" flight with attacking females usually remaining undetected until the moment of larviposition. In contrast. C. apicata landed on or near deer and became objects of attraction eliciting the curiosity of deer and causing them to orient to the fly in a position vulnerable to larviposition. The final phase of attack by C. jellisoni was initiated from a blind spot in front of. and below, the deer's nose, whereas visible C. apicata attacked from perched positions. After flies squirted larvae into deer's nostrils, deer jerked back their heads and sneezed as they simultaneously shook their heads and lowered their noses to the ground. A series of other post-larviposition behavioral responses of deer are described, as is their characteristic fly alert position and behavior. Encounters with C. apicata and C. jellisoni females that larviposited in their nostrils led to the recognition of these flies by educated deer and to their responding with anti-nose-bot-fly behavior resulting in their evading females attempting to tarviposit. Deer did not respond to flies presented for them to smell, but when tethered C. jellisoni hovered in view of experienced deer, deer exhibited the characteristic evasive reactions provoked when wild flies were spotted. Deer also responded similarly when Cephenemyia larvae were "finger inoculated" into their nostrils.