ROADSIDE LIFE. 261 



and they differ from the bees in not having the hind 

 legs fitted for carrying pollen. 



Although the digger-wasps do not provision their 

 nests with pollen cjr nectar, they feed on these sub- 

 stances themselves, and hence are often found on 

 flowers. Many of them are also frequently found in 

 damp places collecting mud for their nests, for some 

 species make their nests entirely of mud, and others 

 that make burrows in wood divide these burrows 

 into cells by partitions of mud. 



Of those that build their nests of mud, the most 

 common are the thread-waisted wasps, so called on 

 account of the form of the first ab- 

 dominal segment (Fig. 236). They 

 make nests of mud attached to the 

 lower surface of flat stones or to "fig. 236.— a thread- 

 the ceilings of buildings. These waistedwasp. 

 nests usually have the form of several tubes an itich 

 or so long placed side by side, and are provisioned 

 with spiders. The spiders are not killed, but stung 

 until paralyzed. The pre}' thus treated remains alive 

 a long time, but is helpless. An egg is laid in each 

 cell with this provision, and then the opening of the 

 tube is sealed up securely. When the larva hatches 

 it finds nicely preserved food right at hand sufficient 

 to nourish it during its growth. Nests of other dig- 

 ger-wasps are described below. 



INSECTS OF SUMACH AND OTHER PITHY PLANTS. 



Many bees, wasps, and digger-wasps build their 

 nests in dead branches of sumach and other pithy 

 plants. Where sumach grows it affords the best op- 

 portunity for the study of the nests of these insects. 



