HYMENOPTERA 



37i 



cussed here although they are among the most interesting of the Hymen- 

 optera because of their remarkable nesting habits. 



Wasps of the genus Trypoxylon. — These are black slender 

 wasps of medium size one of which, T.fngidum, makes its nests 

 here in New York, very commonly in the branches of sumac 

 (Fig. 617). The cells of these nests are separated by partitions 

 of mud and are stored with spiders. 



Mr. and Mrs. Peckham who studied two other species, T. 

 albopilosum and, T. rubrocinctum, in Wisconsin give a very 

 interesting account of the cooperation of the males and fe- 

 males during the nest-building period as follows: 



" With both species when the preliminary work of clear- 

 ing the nest and erecting the inner partition has been per- 

 formed by the female, the male takes up his station inside 

 the cell, facing outward, his little head just filling the 

 opening. Here he stands on guard for the greater part of 

 the time until the nest is provisioned and sealed up, occa- 

 sionally varying the monotony of his task by a short flight." 

 " We have frequently seen him drive away the brilliant green 

 Chrysis fly which is always waiting about for a chance to 

 enter an unguarded nest." " In one instance, with rubro- 

 cinctum where the work of storing the nest had been delayed by 

 rainy weather, we saw the male assisting by taking the spi- 

 ders from the female as she brought them and packing them 

 into the nest, leaving her free to hunt for more." 



Some species of Trypoxylon are mud-daubers. Trypoxylon 

 albitarsis, a shiny black species with white tarsi, builds large 

 nests of mud, which consist of several parallel tubes, often 

 three inches or more in length, placed side by side. These 

 nests are known as pipe-organ nests. Each tube is divided 

 by transverse partitions into several cells, which are provisioned 

 with spiders. The tubes when completed are not covered 

 with an extra layer of mud as is commonly the case in the 

 nests of other mud-daubers. When an adult is ready to emerge n&t'^Tn- 



from the cell in ^ rylon Ms ' 

 which it was de- 

 veloped, it makes a hole through 

 the exposed side of the tube. 



The thread-waisted wasps. — 

 These are the most commonly 

 observed of all of our sphecoid 

 wasps, as certain species build 

 their mud nests in the attics of 

 our houses; and, too, the pecu- 

 liar shape of the body makes 

 them very conspicuous. Most 

 of the species burrow in the 

 ground and store their nests ei- 

 ther with caterpillars or with Or- 

 thoptera. But those best known 

 to us are the mud-daubers. 

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





a. b. c. d* 



Fig. 618. — Nest' of a mud-dauber removed from a wall 

 exposing the cells: a, larva full-grown; b, cocoon, r, young 

 larva feeding on its spider-meat; d, an empty cell. (From A. 

 B. Comstock, Handbook of Nature Study.) 



