54 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 



labium 4, and mandibles 2, making 62 pores in all. The fact that this 

 number is extremely low for any insect may help to explain why these 

 larvae did not respond readily to odor stimuli. 



Fig. 16. — Position of olfactory pores (dots), 12 to 15 so-called taste hairs 

 (Thr) at tip of each ma.xillary palpus, 8 tactile or so-called olfactory hairs 

 (St) at tip of each antenna, and ocelli (Oc) on larva of bean beetle, X 32. 

 A and B, inner and outer sides respectively of right front leg. The number of 

 pores on the legs is nearly constant, and they shift only slightly in position. 

 C and D, dorsal and ventral surfaces respectively of the head and head appen- 

 dages. On the base of each antenna one pore is on the dorsal side and one on 

 the ventral side. On each terminal maxillary segment there is a slit-shaped pore. 



2. SO-CALLED TASTE ORGANS 



Several writers, particularly Nagel (58), have described certain 

 tiny peglike hairs on the mouth parts of insects as taste organs, but 

 no one has ever demonstrated that they perform such a function. 

 Hochreuther (25) found many " Tast- und Geschmackszapfchen " 

 on the maxillary and labial palpi of the water beetle Dytiscus margi- 



