SUMMARY AND CONCLUSIONS. 
The present paper comprises more or less detailed observations 
on some 28 species of Texas Solitary Wasps. It was not written 
for the purpose of entering the discussion of mooted questions of 
instinct and intelligence, but rather of describing clearly and ac- 
curately the actions of some of these delightful little workers in 
their natural haunts. 
My experiments on the mental faculties of wasps have been few 
and therefore of little value. The experiment recorded above on 
the sense of direction I have considered of sufficient value to be put 
down. It certainly has to commend it an absence of artificiality 
having been made by merely varying the natural conditions to which 
trie wasp was already accustomed. In general my observations lead 
me to accord with the opinion held by the Peckhams and others that 
wasps are guided by sight in finding their way — by sight and the 
memory of familiar landmarks in the neighborhood. 
Of the varibility of instincts within a given species there can in 
my opinion be no doubt. The variability in mental traits and dis- 
positions as reflected in the wasp’s actions, seems moreover to be pro- 
portionate to the physicial variability. At any rate, Bembex bel- 
fraegi , the species of Bembidula and Microbembex monodonta, for 
example are all very variable species in size and coloration as well 
as in the demeanor of different individuals. 
All the species of solitary wasps either dig holes in the ground 
for their nests or work with mud in their architectural pursuits. In 
the case of Agenia (Chap. YI ) both kinds of nests are found in the 
same genus, some species digging typical nests in the ground while 
others build mud cells in protected places. This fact alone, it seems 
to me, would justify the setting-up of a distinct genus, Pseudagenia, 
as is done by some authorities. Among the wasps that dig their 
nests we may recognize two methods of excavation : in one the wasp 
utilizes the forelegs to scrape out the dirt loosened by the mandibles ; 
in the other the wasp employs the mandibles both as pick and as 
shovel. Ammophila (Chap. II) and Priononyx (Chap. IX) repre- 
sent the latter method and their nests are composed of a vertical 
tunnel leading straight down from the surface (Fig. 8) to a pocket 
whose long axis lies horizontal (Figs. 18 and 22.) The wasps work- 
ing by the scratching method and employing their forefeet as rakes 
in excavation have simple nests consisting of a tube running ob- 
