962 THE BUTTERFLIES OF NEW ENGLAND. 



and covered with a delicate tracery of raised lines having a kind of wheel 

 pattern. 



The caterpillars are green, with or without a dorsal stripe, and with 

 faint, oblique, lateral lines, the head capable of being extended to a great 

 length. 



The chrysalids are long and slender, almost uniform green, with a full, 

 plump abdomen, covered with a very delicate reticulation of raised lines. 



EXCURSUS XXXV.— THE FRIENDS AND ASSOCIATES OF 



CATERPILLARS. 



Brown ami furry, 



Caterpillar in a hurry, 



Take your walli 



To the shatly leaf, or stalk, 



Or what not, 



Which may be the chosen spot. 



No toad spy you. 



Hovering bird of prey pass by you ; 



Spin and die, 



To live again a butterfly. 



Christina Rossetti. 



One of the most surprising statements which have been made regarding 

 the caterpillars of butterflies is that they are sometimes accompanied by 

 ants, which seem to guard them with great jealousy, running about them 

 with nervous activity, and rushing with open jaws at any creature that 

 approaches. This phenomenon, first observed more than a century ago, has 

 been repeatedly witnessed by others, but owing to the fact that the caterpil- 

 lars in question are very small, usually of the color of the leaf or flower 

 upon which they may be feeding, slow in movement and of a flattened form, 

 they are among the least known of our caterpillars and rarely are seen by 

 the casual observer. For the only caterpillars which are thus accom- 

 panied are, as far as known, those which belong to the subfamily of the 

 Lycaeninae, and indeed to the tribe of Lycaenidi or blues, minute butter- 

 flies whose caterpillars rarely attain a length of an inch. The cause of 

 this friendship and association is not far to seek, for a slight observation 

 of the action of the ants will show that they have a reason for their devo- 

 tion to the caterpillars. They tend these as they tend plant lice, because 

 each of them has the power of exuding, from special glands at the extrem- 

 ity of the body, a droplet of fluid having a saccharine character, and 

 thus attractive to ants, whose fondness for sweet things is well known to 

 every housekeeper. In the butterfly caterpillars, as has been detailed 

 elsewhere in the body of this work, this gland is situated in the middle of 

 the body on the seventh abdominal segment, and now and then, at the 

 solicitation of the ants, by the stroking of their antennae, is evaginated 

 and a droplet of fluid exposed, which the ants greedily lap up. 



Now, although the only caterpillars attended by ants belong to the 



