98 ENTOMOLOGY 
each seated in a pit, or cup, and connected with a nerve fiber 
(Figs. 129, 130). In some cases, however, it is difficult to 
Fic. 128. 
decide whether a given organ 
is gustatory or olfactory, owing 
Under side of left maxilla of 
wasp, Vespa vulgaris. p, palpus; pr, 
protecting hairs; tc, taste cup; th, the 
tactile hair.—After WILL. 
the 
In dragon flies, however, this 
sense is relied upon far less 
than that of sight. 
Organs of Smell.— By 
means of simple but conclu- 
sive experiments, Hauser and 
others have shown that the 
antenne are frequently olfac- 
tory—though not to the ex- 
clusion of tactile or auditory 
functions, of course. Hauser 
found that ants, wasps, vari- 
ous flies, moths, beetles and 
kinds of structures. In 
fy i to the similarity between these 
\ SUNT ey tc two 
\ Ye PPoANT, 
aquatic insects, indeed, the 
senses of taste and smell are not 
differentiated, these forms havy- 
ing with other of the lower 
animals simply a ‘ chemical ”’ 
sense. 
Smell.—In most insects the 
sense of smell is highly efficient 
and in many species it is incon- 
ceivably acute. Hosts of in- 
sects depend chiefly on their 
olfactory powers to find food, 
for example many beetles, the 
flesh flies and the flower-visit- 
ing 
moths; or else to discover 
opposite sex, as is notably 
case in saturniid moths. 
Longitudinal section of gustatory 
end-organ (tc, of Fig. 128). c, cutic- 
ula; h, hypodermis; sc, sensory cell; 
tc, taste cup.—After WILL. 
larvee, which react violently toward the vapor of turpen- 
