butterfly radiation

[Michael Gochfeld]

Bruce Walsh raised a provacative question that I'd never thought much 
about.  Why don't butterflies radiate like some other groups.  On the 
Galapagos there are a number of famous radiations (finches, for 
example), but I don't remember there being much in the way of 
butterflies at all, much less a radiation.  Is it because there were no 
butterflies there historically and they are only recent (perhaps human 
assisted arrivals).  

Is there some intrinsic biologic feature that inhibits radiation?

Mike Gochfeld