Thank you all for your ideas.  I am glad to see I'm not the only
one for whom ethyl acetate seemed to take ages.
Has anyone ever tried Raid, or any kind of insecticide?
Aren't there some sorts that are especially deadly to bees?
Although I'm not sure how you'd get them into the bottle...
 
 
I will try all these methods with the paper towels and tissues
this coming season.  The cooler/freezing works, but usually
wherever I am in the field is a good half hour's walk from the
closest place one could drag a cooler.  (Yes, I know that's what
grad students are for, but there's only one of me!  :-)    )
Liz Day
 
University of Illinois at Chicago
[log in to unmask]