A friend of mine in Laramie Wyoming reported snow yesterday; here in southern California we’re baking in nearly 100 degree temperatures, but that means that insects are still out, and I can still photograph them!  One of my favorite insects is the sphinx moth.  Sphinx moths are a family of moths (Sphingidae) comprising about 1,200 species; the white-lined sphinx moth (Hyles lineata) is very common here in southern California.

White-lined sphinx moth, 2009

I caught this individual flying around in my garage one evening (they’re nocturnal).  After catching it, I did what any good biologist would do: I put it in the fridge.  Why?  Because I wanted to do what any good photographer would do: take pictures of it.

After letting it cool down, I placed the moth on some vegetation in my front yard.  Using my 300/4 lens with a 1.4x teleconverter, I was able to fill most of the frame with the moth at the minimum focusing distance.  I used a flash with -1 2/3 stops compensation to act as a fill flash.

Moths–like all insects–are ectotherms, meaning they are “cold-blooded”.  In other words, they have to derive their body heat from somewhere other than metabolic sources.  You and I are endotherms–we produce our own body heat via our metabolism.  So, as this guy warmed up from being in the fridge it started to move around more and more.  But, it still needed more heat to be able to fly.  That’s when things got interesting.

Ectotherms have to derive their body heat from external sources (usually the environment–this is why you see lizards and snakes sunbathing), but sphinx moths display something called ‘periodic endothermy’–they flap their wings at a very rapid pace to build enough body heat to be able to fly:

White-lined sphinx moth beating wings in a display of ‘periodic endothermy’, 2009

Beating the wings in this manner generates a large amount of heat, which can then be used for flight.  This moth displayed this behavior for about 3 minutes, then took off.  It was a great interaction, a good physiology lesson, and I got some great pictures out of it!