Insect Study 



341 



The tobacco sphinx moth witJi 



tongue extended. 



Photo by M. V. Slingerland. 



able long tongues, being sometimes 

 twice the length of the body. 

 When not in use, the tongue is curled 

 like a watch spring in front and beneath 

 the head; but of what possible use is 

 such a long tongue! That is a story for 

 certain flowers to tell, the flowers which 

 have the nectar wells far down at the 

 base of tubular corollas, like the petunia, 

 the morning glory or the nasturtium; 

 such flowers were evidently developed to 

 match the long-tongued insects. Some 

 of these flowers, like the jimson weed and 

 nicotina, open late in the day so as to be 

 ready for these evening visitors. In 

 some cases, especially in the orchids, 

 there is a special partnership established 

 between one species of flower and one 

 species of sphinx moths. The tobacco 

 sphinx is an instance of such partner- 

 ship ; this moth visits tobacco flowers and helps develop the seeds 

 by carrying pollen from flower to flower; and in turn it lays its 

 eggs upon the leaves 

 of this plant, on which 

 its great caterpillar 

 feeds and waxes fat, 

 and in high dudgeon 

 often disputes the 

 smoker's sole right to 

 the "weed." Tobacco 

 probably receives 

 enough benefit from 

 the ministrations of 

 the moth to compen- 

 sate for the injury it 

 suffers from the cater- 

 pillars; but the owmer ^^'^ '"'^'^' ^f the sphinx caterpillar, n-hich 

 of the tobacco field, feeds on tomato. 

 not being a plant, does '^^°'° ^^ ^^- ^- SHngeriand. 

 not look at it in this equitable man 



The sphinx caterpillars are leaf eaters and each species feeds upon a 

 limited number of i)lants which are usually related; for instance, one 

 feeds upon both the potato and tomato; another upon the Virginia 

 creeper and grapes. In color these caterpillars so resemble the leaves 

 that they are discovered with difficulty. Those on the Virginia creeper, 

 which shades porches, may be located by the black pellets of waste 

 material which fall from them to the ground; but even after this unmis- 

 takable hint I have searched a long time to find the caterpillar in the 

 leaves above; its color serves to hide the insect from birds which feed 

 upon it eagerly. In some species, the caterpillars are ornamented with 

 oblique stripes along the sides, and in others the strij^cs are lengthwise. 

 There is often a great variation in color between the caterpillars of 



