Quote Originally Posted by Greengage View Post
This is probably the best book ever written on Bumblebees even still
http://www.buzzaboutbees.net/support...bumblebees.pdf
You're not wrong! That is a *cracking* book, packed with insight and detail I haven't seen elsewhere. Thanks for posting the link GG.

Two points on cuckoo bees. They have smokey wings which I think you can see in Kitta's photos. They also have thickened cuticles which serve them well in their tussles inside the nests of other species before they take over. Sladen describes the process of nest usurpation really well.

Why smokey wings? I reckon it is a side effect of having genes that give thick cuticles.