208 



NATURE SKETCHES IN TEMPERATE AMERICA 



The 



Jug-making 



Wasp 



F the various solitary wasps the 

 jug-maker is one of the most in- 

 genious architects. When she is 

 about ready to perpetuate her 

 species, she selects a small branch of willow, 

 beech, or perhaps a weed, and thereupon sets to 

 work, building a little nest of mud and sand, which, 

 when completed, presents the form of a miniature 

 water-jug. In this jug she stores one or more green cater- 

 pillars which she has previously paralyzed by a sting from her 

 ovipositor. She then lays her egg on one of the caterpillars, 

 which furnishes nourishment for the developing larva after 

 it hatches. The period of nest building, in those I have 

 observed, is in the latter part of July. 



One day a partly constructed nest of this wasp was found on 

 the flower stem of a dried heath plant. When first visited in 

 the forenoon, the wasp had about two-thirds of the structure 

 completed. The incomplete nest had a hole of considerable 

 size left open at the top. Some hours after, it was found that In 

 the meantime the wasp had finished the nest; the opening having 

 been narrowed into a neck and completed with a circular pro- 

 jecting edge. (See photographic illustration.) Through the 

 small round opening inside a green caterpillar could be seen. 

 On the outside of this nest were a number of protruding nodes, 

 of the same material forming the nest. The significance of this 

 ornamentation is not altogether clear. The first row of these 

 small nodes encompasses the forward third of the globular 

 nest, more or less regularly disposed, while about seven more are 



