BEES AND WASPS OF BARTICA 373 



the rainfall. It will be noticed that in April, only 3.09 inches 

 are recorded. This is far below the usual average of the 

 month, and in a normal year the curve would rise steadily 

 from February to June. 



For convenience I have divided the one hundred and 

 seven species into six general divisions according to their 

 nesting habitats. It will be noted that the species belonging 

 to all but the sixth division have, in one way or another, taken 

 advantage of changes brought about by man, a fact that 

 seems to me remarkable in view of the short time that has 

 elapsed since many of these changes have occurred. The 

 divisions and number of species belonging to each are as 

 follows : 



1. Nesting only in trails 40 species 



2. Nesting in trails and forest 18 " 



3. Nesting in houses or outbuildings 18 



4. Nesting in houses and in open trails 2 " 



5. Nesting in houses, trails and in the forest 5 



6. Nesting only in forest 18 



The nesting haunts of six species were undetermined. 



No attempt will be made to give a list of these one hun- 

 dred and seven species in the present work. They are men- 

 tioned only with a view to give an idea of the immense field 

 of work open to the entomologist in Guiana. I have made 

 observations of one kind or another on almost all of these 

 species, but the data accumulated is not sufficiently complete 

 to prepare more chapters than those which follow. 



I found exquisite types of nests. Some were like tiny 

 barrels of emerald moss, one was fashioned from wasp-made 

 paper, layed on in strips of varied colors, others were invert- 

 ed domes of sweet smelling resin. Here was one of forest 

 mould, a tube-like structure with a flared entrance. There 

 were tiny purses made of cob-webs, plant down and lichens. 

 They hung on spiral stems from the under sides of leaves 

 and in the eaves of outbuildings. Some nests were mere tun- 



