304 THE WASPS. 



wasp- architect with a kind of triumphant song, which, as it 

 began to work, changed into a joyful busy hum. The little 

 clay pellet was laid on the edge of the nest wall, and then 

 spread along it with jaws and under-lip. The building was 

 trodden down all round and smoothed with the feet. The 

 completion of the whole occupied about a week. The 

 interior of these nests is filled up with half-dead spiders, 

 which the mothers bring for the food of the larvae and 

 reduce to this half-dead condition by stinging them, as do 

 these wasps with all insects destined for the nourishment 

 of their young. 



Another species, also observed by Bates (Trypoxylori), 

 builds its three-inch long nest in the form of a water bottle, 

 and makes such a noise over it that when several together 

 are building a house the neighborhood is in quite a commo- 

 tion. They also emit very different notes when they fly in 

 with their load or away, and when they are at work. 



In Europe there are different species of unsocial wall 

 wasps, which mostly belong to the Odynerus species, and dig 

 the holes for their young several inches deep in old clay 

 walls or firm sand banks. They also, in remarkable fashion,, 

 make outside long projecting and very artistically-built 

 chimney-like tubes, which serve as protective entrances to- 

 the nests. An egg is laid inside with from ten to twelve 

 half-dead caterpillars piled upon each other, on which the 

 hatched larva feeds until it begins to spin. The mother 

 knows exactly how many and what sized caterpillars it must 

 bring for each larva, and seems always to select the same 

 species for her young. Wesmael (in Brehm, loc. cit. ix., 

 p. 240) relates that a mason wasp pinched between its jaws 

 a caterpillar rolled up in a leaf until it left its sheltering 

 cover and fell a prey to the hunter ! 



" In the first days of June," says Blanchard (lot. cit. 

 p. 398), " we found ourselves, myself and two friends, in the 

 De'partement du Nord, at a short distance from Denain, 

 when our notice was called to an attractive spectacle. The 

 road was bordered by a bank about two metres high, edging 

 a large clover field. The bank was of firm soil and faced 

 the full mid-day sun. Thousands, nay, hundreds of thou- 

 sands of wasps were flying over the clover field, and picking 

 little green caterpillars off the plants with indescribable eager- 

 ness. Others were busy digging holes in the earth, building 



