BEES. 



submarginal cell. Ammobia (formerly called Spliex); 

 pcnnsylvanicum has black abdomen and legs; for ichneu- 

 moneum, see Plate XCII. The nests are stocked with 

 grasshoppers. 



In Spliex (in a limited sense) the petiole is composed 

 of the entire first and part of the second abdominal seg- 

 ment. Species of this genus stock their underground 

 nest with paralyzed caterpillars. 5. abbreviate, (abdomen 

 black) and procera (abdomen partly red) usually have 

 complete, transverse striae on the back between the wings. 

 Plate XCII shows urnaria. Psammopliila is considered 

 by some to be a subgenus of Sphex, and, like it, has a U- 

 shaped dorsal area at the hind end of the thorax, but the 

 petiole is not especially long and is one- jointed, the second 

 abdominal segment being bell-shaped. 



Chalybion and Sceliphron have a U-shaped area on top 

 of the thorax at the hind end. See Plates XCI and XCII ; 

 both species provision their clay nests with spiders. The 

 markings of S. cementarius, the Mud-dauber, vary con- 

 siderabty; its flat nests are to be found on the rafters of 

 nearly every garret. 



APOIDEA 







Although wasps visit flowers, they usually do so in 

 their individual interest : to secure food for themselves and 

 not to provide for their offspring. Bees, on the other hand, 

 not only eat pollen and nectar themselves but, except for 

 the "cuckoos" which lay their eggs in other bees' nests, 

 store their nests with honey (modified nectar) and pollen. 

 Although they thus take, in the aggregate, large quantities 

 of pollen, they are of great benefit to the plants because 

 they, incidentally and unconsciously, transfer this sub- 

 stance from one flower to another, thus fertilizing the 

 ovum, which develops into a seed. Male bees have 13- 

 jointed antennas and 7 visible, abdominal segments; 

 females, one less of each. Only the Bombidte and Apidas 

 have developed a "worker caste." In other families, the 

 mother does the work of provisioning the nest, carrying 



439 



