36 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8I 



Structures have been considered both tactile and gustatory in function. 

 Lepidopterous larvae bear on their antennae and mouth parts variously 

 shaped sense hairs, some of which have been called taste organs, some 

 touch organs, and others smelling organs. 



Each maxilla on the codling moth bears about 50 pegs or about 100 

 for the entire proboscis. Female No. 3 had 93 of them (fig. 5, D, Pg). 

 They are always found on the distal half of the maxilla and are 

 usually six-sided (fig. 5, F to H) but a few are five-sided. Each one 

 (fig. 5, I) arises from the proboscis as a fluted column and terminates 

 in five or six sharp pinnacles, which surround the innervated hair. 

 If aqueous liquids, or odors, in order to stimulate the nerves inside 

 the hairs, can pass cjuickly through the chitinous walls, we can then 

 safely call them taste organs, or smelling organs ; if such a condi- 

 tion is not true, they are certainly nothing more than touch receptors. 

 The writer has repeatedly objected to the chemical-sense assumption, 

 but believes that smell and taste in insects are inseparal)le and that 

 the olfactory pores are their only receptors. Figure 12 shows the 

 similarity of olfactory and gustatory organs in the higher animals and 

 that the stimuli do not pass through any membrane in order to reach 

 the nerves. 



Let us now consider the chemoreceptors found by Minnich on the 

 tarsi of Initterflies and flies. The two species of butterflies used by 

 Minnich (Co) may often be seen to alight on injured tree trunks or 

 on decaying fruit in orchards, apparently for the purpose of feeding 

 on the exuding sap of the tree or on the juice of the fallen fruit. In 

 the presence of food it was further observed that the proboscis 

 would uncoil and then coil up again in a definite manner. Minnich 

 called this reaction of the proboscis a proboscis response, and later 

 made use of it solely in measuring or weighing the responses of 

 butterflies to various liquids. In order to determine the responses of 

 the tarsal chemoreceptors, and at the same time to control the olfactory 

 responses, maaiy experiments with butterflies in confinement were 

 conducted by using an ingenious and specially constructed apparatus. 

 Briefly stated, the apparatus consisted of a shallow dish (fig. 11, B, d) 

 covered with wire screen {s), in the center of which are two small 

 rectangular openings, which lie just above two small rectangular 

 tin pans (a and h) inside the dish, each containing several layers 

 of cheesecloth. The cheesecloth in one pan (a) was wet with apple 

 juice and that in the other pan {b) with distilled water; and the 

 shallow dish was also full of apple juice. A butterfly to be tested was 

 held Ijy the wings with a spring clothes-j^in in position / ; that is, 



