Smaller than the female, and very different in appearance.
The numerous parasites of which we have spoken usually deposit their eggs in punctures in the bodies of caterpillars or other immature insects, which the grubs devour from within during the life of their victim, leaving it to die when they themselves have reached their full growth.
Intermediate between the boring and stinging insects of this order comes the small family of the Ruby-tailed Flies. These are brilliantly coloured bronze-red, blue, or green metallic four-winged flies, with the thorax covered with large depressions, and the abdomen smooth, and usually composed, as seen from above, of one large, smooth joint, and one or two much smaller coarsely punctured ones beyond it, the last ending in a variable number of short teeth. They roll themselves up in a ball when alarmed, and are parasites, depositing their eggs in the nests of other insects. An entomologist once saw a ruby-tailed fly hurled to the ground by a mason-bee which had built her nest in a hole in a wall. The fly rolled herself up into a ball, when the bee bit off her wings, and then flew away. But as soon as she was gone the wingless fly stretched herself out again, and climbed up the wall to the bee's nest to deposit her eggs.
CRŒSUS BUTTERFLY OF BATCHIAN
Male natural size
Photo by W. P. Dando F.Z.S. Regent's Park. Printed at Lyons, France.
CRŒSUS BUTTERFLY OF BATCHIAN.
Female slightly reduced