California’s Butterflies

Mating

At Right: Two mating adult Euphilotes ancilla (enoptes complex) butterflies.

Mating in butterflies is complicated.  Various papers suggest there are various dances and other behaviors that are important in the decision process for females of different species.  There are long and short distance visual cues and short range chemical cues.  But certainly the timing at which a male finds a female can be very important in the success of mating by a male.  If a male finds a female that has already mated she will be very unlikely to want to mate again and she will refuse his advances, but if a male finds a female that has freshly eclosed from a chrysalis, she may be less likely to refuse his advance.  For this reason Quino checkerspot males can sometimes be found searching for freshly emerged females amongst vegetation in the early morning.

 

It is believed that with many butterfly species mating occurs on hilltops.  This behavior of males searching for mates on hilltops is called hilltopping behavior.  With these species very few females are observed on hilltops.  Most males observed on hilltops are ones that are chasing each other or perching at some position where the male can observe all butterflies flying over the hilltop.  Often every butterfly observed flying by is chased by the hilltopping males.  Of those females that are observed on hilltops most have been either found mating with males or are unmated.

 

With other butterflies, males search for females along drainages.  In this case, males patrol up and down a drainage looking for females.  When there are two closely related butterflies in the same area, one species will exhibit the hilltopping behavior, while the other will search for mates along drainages.  The western tiger swallowtail and the closely related pale swallowtail exhibit these different mating behaviors.  The pale swallowtail exhibits the hilltopping behavior while the tiger swallowtail patrols drainages.  Separating the different mating behaviors reduces the number of mix-ups between these closely related species.

 

Once a male butterfly chases a female down and gets her to land, he often exhibits a wing fanning behavior.  He fans his pheromone over the female and twists his abdomen towards the posterior end of the female.  During this process he probably also tastes the female pheromone on the posterior end of the abdomen of the female.  If he is successful at mating she will allow him to connect to her and he will remain facing the same direction as the female.  When he feels he has connected completely he will turn around and face away from the female.