Wasps, Bees, and Ants 499 



as the social wasps (yellow-jackets and hornets) do. In this family are 

 found diggers, and miners in the earth, carpenters making their nests in 

 twigs or boards, as well as masons or clay-handlers. The species of the 

 genus Odynerus are numerous; in appearance they resemble the yellow- 

 jackets, but are smaller and more slender. They are given to taking advan- 

 tage of any deserted nest of another wasp, or of some already existing hole 

 or tunnel, to save themselves the trouble of mining or moulding a nest of their 

 own. Riley found an Odynerus cell in the tunnel through a spool, and Ash- 

 mead found one in the keyhole of a door-lock. The familiar, long, thread- 



FIG. 701. FIG. 702. 



FIG. 701. A vase mud-nest of Eumenes sp. (Natural size.) 

 FIG. 702. Nest of a mud-dauber wasp. (Natural size.) 



waisted, nervous, black-and-yellow or steel-blue mud-daubers that build 

 several tubular cells an inch or more long side by side of mud, plastered to 

 the under side of a porch roof, on ceilings, under eaves, or under flat stones, 

 belong to the genus Pelopceus (PI. XII, Fig. 15) of the large family Sphe- 

 cidae. These cells are provisioned with paralyzed or dead spiders. Another 

 smaller kind of mud-dauber is Agenius, a genus of the Pompilidiae. The 

 tiny mud-cells of these wasps, built in crevices or on stones, are also pro- 

 visioned with little spiders, often with their legs torn off. Originally the 

 mud-daubers built their nests in hollow trees or under overhanging rocks, as 

 they do yet sometimes; but they mostly nowadays take advantage of the safe 

 and convenient places man arranges for them. 



Of Sharp's fourth group, the true diggers or miners in the ground, I 

 have already described a typical species in the Ammophila of the San Fran- 

 cisco Bay salt marshes. There are many species of this genus, and they 

 are found all over the country. The great golden digger, Sphex ichneu- 



