Grrr! said the Tiger

WE tried for ages to identify this interesting fly we found on our window screen. It was on something white and we couldn't tell if it was feeding on bird droppings or if it was some kind of nest/egg collection. Whatever the white patch was, the fly was quite attached to it. We picked the fly up to examine it, and it flew away, then a short time later was back again and even returned the next day.

It was quite large - maybe 2cm. Plump and black, with a fuzzy body, huge eyes and a curious pattern on its wings. We couldn't tell if the wings had patches of white or patches of see through.

Finally a few days later we found a picture of the tiger bee fly Xenox tigrinus . Emma astutely pointed out that tigers have stripes not spots and why wasn't it called a leopard bee fly? Apparently they lay their eggs in the nests of carpenter bees and their hatching larvae then eat the bee larvae. The white stuff on the window screen wasn't eggs, then.