SOME SILKWORM MOTH REFLEXES. 



VERNON L. KELLOGG. 



Silkworm moths, Bombyx mori, are sexually mature and eager 

 to mate immediately on issuing from the pupal cocoon. They 

 take no food (their mouth parts are atrophied), they do not fly, 

 they are unresponsive to light ; their whole behavior, in fact, is de- 

 termined by their response to the mating and egg-laying instincts. 

 We have thus an animal of considerable complexity of organiza- 

 tion, belonging to a group of organisms well advanced in the 

 animal scale, in a most simple state for experimentation. 



The female moth, nearly immobile, protrudes a paired scent- 

 organ from the hindmost abdominal segment, and the male, walk- 

 ing nervously about and fluttering its useless wings, soon finds 

 the female by virtue of its chemotactic response to the emanating 

 odor. Males find the females exclusively by this response, but 

 orient themselves for copulation (after reaching the female) by 

 contact. When two males accidentally come into contact in their 







moving about they try persistently to copulate. 



A male with antennae intact, but with eyes blackened, finds 

 females immediately and with just as much precision as those 

 with eyes unblackened. A male with antennae off and eyes un- 

 blackened does not find females unless by accident in its aimless 

 moving about. But if a male with antennae off does come into 

 contact, by chance, with a female it always (or nearly so) readily 

 and immediately mates. The male is not excited before touching 

 the female, but is immediately and strongly so after coming in 

 contact with her. Males with antennae on become strongly ex- 

 cited when a female is brought within several inches of them. 



o 



The protruded scent-glands of the female are withdrawn into 

 the body immediately on her being touched by a male. If the 

 scent-glands are cut off and put wholly apart from the female, 

 males are as strongly attracted to these isolated scent- glands as 

 they are to unmutilated females ; on the contrary they are not 

 at all attracted to the mutilated females. If the cut-out scent- 

 glands are put by the side of and but a little apart from the 



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