#2
I think yiou will find the answer in this article:
Quantification of cantharidin in canthariphilous ceratopogonidae (Diptera), anthomyiidae (Diptera) and cantharidin-producing oedemeridae (Coleoptera)
0098-0331 (Print) 1573-1561 (Online) ---
Journal Journal of Chemical Ecology
Publisher Springer Netherlands
#3
According to the german wikipedia, the importance of this is still unclear.
I tried to access the article above, but it is not free...