BEES. 



Sphecodes, the Wasp-bees (so-called from their re- 

 semblance to small wasps, Plate XCIII), have had cham- 

 pions who opposed the charge that they lay their eggs in 

 nests prepared by others, their young devouring the food 

 and doubtless the young of their hosts, but there is strong 

 evidence that they are supported by their relatives, Ilalictus, 

 and possibly by other bees. The other Halictidae usually 

 nest in the ground, frequently making branched tunnels, 

 many individuals selecting the same restricted area for 

 their burrows. Some species of Halictus, in the limited 

 sense, are very small and are called Sweat-bees because 

 they seem fond of alighting on perspiring humanity. 

 Some of the species are among the first bees to appear in 

 the spring. The pupas are enclosed in transparent, skin- 

 like cocoons. 



ANDRENID.E 







These are usually black (with pale pubescence), medium- 

 sized bees. They are closely related to the Halictidas 

 but the basal vein is almost, or quite, straight, and the 

 face, at least of females, has pubescent depressions. In 

 M ditto, (apical joint of antennas obliquely truncate; ocelli 

 placed in a curve) and Andrena (that joint not obliquely 

 truncate; ocelli placed in a triangle) the first submarginal 

 cell is conspicuously longer than the third but in the 

 southern Nomia it is about the same length. Our only 

 species of Melitta is americana. 



Andrena (Plate XCIII), our principal genus, is extremely 

 well supplied with species. They all seem to nest in the 

 ground but the sites chosen for their burrows vary greatly. 

 Some species make simple tunnels, others branched, but 

 none seem to do much more than smooth the sides and 

 stock each tunnel or branch with a pill of pollen and an 

 egg, filling the opening, of course, with loose dirt. At 

 least some of the species have two generations a year, and 

 it is not unlikely that, in some cases, what we now call 

 distinct species are merely the alternate generations of 

 one. 



441 



