Western tiger swallowtail butterfly.

 

I look forward to this time of year with great anticipation, not the least reason being the return of swallowtail butterflies.  There are many species of swallowtail, all of them large, colourful lepidopterans that are easy to identify at a distance.  It is a little trickier coming up with a particular species moniker, but that takes only a bit of time and a decent field guide.  There are 11 species of Papilio in BC; yesterday I saw three of them where I am staying in Winfield.  The other two were possibly the Canadian and pale swallowtails.

The western tiger swallowtail is univoltine (a new word for me - it means it has only one generation per year) here in BC.  Farther south the species may go through two or even three generations (guess which word specifies that status? - polyvoltine) in a year.  Their southern range goes all the way to southern California.  I only ever see them up here in mid to late spring.

The caterpillars feed on a variety of tree species but include alder, apple, and birch trees.  When the larvae are mature, they drop to the ground and search for a suitable place to pupate.  This often entails crawling over modest distances until a protected venue can be found.  There they moult for a final time and emerge in the pupal form.  They overwinter as such and then finally emerge as adults in the spring.  The longest-living adult on record was a venerable 39 days-old.  

Although I have photographed this species several times in the past, I always enjoy capturing new images of them.  They seem especially fond of lilac flowers, which are currently just starting to ebb.  I may end up with a few more photos in the coming days.

Thanks for reading. 

Eric Svendsen     www.ericspix.com