Last autumn a dangerous bough had to be taken down from the top of a high elm-tree in my garden. It was perhaps sixty feet above the ground and it came down with a crash and broke up into little pieces. I picked up one of these tubes and galleries, which I knew were insects' work. But there was something much more exciting than this. A number of the galleries had blind ends to them, and at the bottom of these were masses of dead blue-bottles, tightly packed, which rested on small pillows of sawdust, and had long plugs of sawdust above them.
This is what the piece of elm-bough looked like. You will be able to see the little tunnels, and the stores of blue-bottles, which are black-looking, and the plugs of sawdust, in which the pupa cases of the wasp-grubs are hidden. You can see one pupa about half way up
I opened one of the long sawdust plugs and found, as I half expected to find, that at the end of it next to the blue-bottles, was a small brown papery cocoon, and that inside the cocoon was a wasp grub. I need hardly tell you that I collected a lot of the wood, and kept it carefully through the winter, and tried to make the little grubs as much at home as if they had stayed up in their tree. To do this I had to keep the wood in moist and rather dark surroundings. Then when the spring came round I sometimes put the wood in the sunshine, when it was not too hot, and in the first week in June I was rewarded for my trouble, for the little wasps hatched out in dozens, and so I was able to find out what they were.
Look up to the top of the trees some warm summer day, and think of the blue-bottle hunt which may be going on above us, and of the wonderful little hunter, Crabro.
This is one of the cocoons of Crabro in the elm-bough. Crabro is just going to hatch out. You can see the little black hole where she has started gnawing
SPINIPES THE SAND-WASP
(MIDSUMMER DAY)
AUTHOR'S NOTE