Field Studies of the Non-Social Wasps 407 
were seen carrying out load after load of sawdust from 
a burrow in a log which they were enlarging by biting 
out the wood. These instances, together with their pres- 
ent occupancy of the abandoned bee holes, shows wide di- 
versity in their selection of home sites, and willingness 
to take almost any ready-made domicile and make it over 
rather than to carry mud and build, as do their pipe-or- 
gan-nestbuilding sisters. Yet after all there is a kinship 
to this mudnesting species, for T. clavatum carries mud 
to partition and plug up the tunnel that she has appro- 
priated for herself. This diversity in selection of habi- 
tat is very interesting in that it mirrors the versatility 
of nesting habits in the genus, or rather the family, since 
this consists of but one genus. If we consider other 
genera of wasps, such as Pompiloides, or Sphex, or Chlo- 
rion, we find that all the members of each group nidify 
in a similar manner. But here in Trypoxylon, we find 
certain species building nests of mud, e. g., T. albitarsis 
=politum ; some live in stems of plants, as T. frigidum 
Mm syringa stems (Glover, Rep. Com. U. 8S. Dept. Agr. 
1877, p. 104) and stems of sumac bushes (Peckhams, 
Wasps Social and Solitary, p. 194); 7. figulus uses holes 
in posts and straws in thatch (Westwood, Introd. 2: 194. 
1840) and in the galls of Cynips kollari (Billups, Entom. 
#8: 47. 1895) and was seen to enter nests of Odynerus re- 
niformis (Morice, Ent. Mon. Mag. 42: 216-220. 1906) ; T. 
johnsoni in stems of soft wood (Rau, Wasp Studies 
Afield, p. 137-139), and in the soil clinging to the roots 
of an upturned tree (Rau, Trans. Acad. Sci. St. Louis, 
24: 22. 1922); T. aurifrons ‘‘constructs its clay cells in 
the shape of water jugs’’ with a distinct neck and well- 
formed mouth (Step, quotes Bates, Marvels of Insect 
Life, p. 426), and cells or tubular structures, building 
rows of them together in corners of verandas (Weed, In- 
