HYMENOPTERA 



967 



peculiar shape of the body makes them very conspicuous. Most of 

 the species burrow in the ground and store their nests either with 

 caterpillars or with Orthoptera. But those best known to us are the 

 mud-daubers. 



The mud-daubers make nests of mud attached to the lower 

 surface of flat stones or to the ceilings or walls of buildings. These 

 nests usually consist of 

 several tubes about 

 twenty-five millimeters 

 in length placed side by 

 side (Fig. 1201) and are 

 provisioned with spiders. 

 The mud-daubers may 

 be seen in damp places 

 collecting mud for their 

 nests, or exploring build- 

 ings in search of a place 

 to build. They have a 

 curious habit of jerking 

 their wings frequently in 

 a nervous manner. There 

 are in this country two -^^^ 

 widely distributed and 

 common species of mud- 

 daubers; these are the 

 blue mud-dauber, Chaly- 



bion ccBrulium, which is steel blue with blue wings, and the yellow 

 mud-dauber, Sceliphron cementdrium, which is black or brown with 

 yellow spots and legs. The latter of these species has been commonly 

 described under the generic name Pelopcsus. 



The tool-using wasps, Ammophila. — Among the members of the 

 Sphecinse, that burrow in the ground and store their nest with cater- 

 pillars are certain species of the genus Ammophila. These are of 

 especial interest on account of the habit, first observed by the 

 Peckhams, of pounding down the earth with which they close their 

 burrow by taking a stone or some other object in their mandibles and 

 using it as a hammer. 



The genus Chldrion, formerly known as Sphex, includes species 

 which are among the most common of flower visitors in the warmer 

 parts of our country, and are among the largest and most handsome, 

 and therefore most often observed of our wasps. In the West the 

 common, very large, all metallic green Chldrion cydneum is a very 

 striking insect; and in the East Chlorion ichneumdneum, which is 

 brownish red with the end of the abdomen black is the most noticeable. 



1 201. — Nest of a mud-dauber removed from 

 a wall exposing the cells: a, larva full-grown; b, 

 cocoon, c, young larva feeding on its spider- 

 meat; d, an empty cell. (From A. B. Comstock, 

 Handbook of Nature Study.) 



Subfamily PSENIN^ 



This subfamily includes two tribes, the Psenini and the Pemphre- 

 donini; each of these has been regarded as a separate subfamily or 

 family. 



