1918] Leaf Eating Crane- Fly 75 



but perish either from starvation or are preyed upon by spiders 

 and insect predators. 



In nine days (July 16), the larvae had increased in length to 

 5.84 mm. long, although a few were only 3.57 mm. Except for 

 the green color of the alimentary canal, they were of a dirty 

 grayish hue. Even in the young stages they display all the 

 characteristic behavior and movements of the full-grown larva, 

 which can be most aptly compared with those of "measuring 

 worms" or "looper" caterpillars (Geometridae). 



The first larval moult occurs after a period of about 18 to 21 

 days, although in some cases it did not take place for 5 or 6 weeks. 

 Growth is very slow and quite in accord with the sluggishness 

 displayed by the animal. Previous to this first moult, the 

 larvae, in moving over the leaves, become invested with particles 

 of their excreta which adhere readily to the skin as if it were 

 coated with a sticky substance. The freshly-moulted larvae 

 are almost translucent white, and the two tracheal trunks with 

 their ramifications are readily distinguishable by the aid of the 

 binocular microscope. 



The larvae have the power, when young, of secreting a silken 

 thread from the mouth, which is probably the product of the 

 salivary glands. They frequently adhered by this thread to the 

 camel-hair, water-color brush used in transferring them from one 

 leaf to another. The power to produce this thread is but limited, 

 and on no occasion was it observed to be of any great length. 

 Usually, it measured not more than half-an-inch. 



The second-stage larvae gradually assume a leaf-green color 

 as they continue to feed, obscured in some by a brownish pig- 

 ment beneath the cuticle. Laterally, in the more mature first 

 stage larvae, on each side of the median, dorsal line, there runs 

 an irregularly-defined, brownish-gray band somewhat inter- 

 rupted intersegmentally. In the larvae of the second stage, 

 these bands may still persist or give place on each segment to 

 two similarly colored lines representing a V, the arms of which, 

 however, do not meet and fuse posteriorly. On each side, the 

 band on any one segment is parallel with that on the others. 



Towards the end of July, more accurately, on the 26th, 

 coincident with the dying off of the food-plant, T. grandis, the 

 larvae which had now assumed a size of 8.32 to 9.00 mm. long, 

 became quiescent and ceased to feed. Previously, in the middle 

 of July, when the larvae in the breeding-cages were transferred 



