THE GEAPE LEAF-FOLDER. 7 



LIFE HISTORY AND HABITS. 



The moths of the grape leaf-folder issued in greatest numbers 

 during the early part of May, from pupse overwintered in jars in the 

 out-of-door rearing shelter at Washington, D. C. This maximum- 

 emergence date will vary, of com*se, with different localities, owing to 

 variation in humidity and temperature. Moths were obtained over 

 a much longer period, including the latter part of April, aU of May, 

 and most of June. 



About 60 minutes is consumed by the insect in emerging from the 

 pupal skin, the operation commencing with a circular abrasion at the 

 head end. The number of females to issue was greater than the 

 number of males by approximately seven to one. Numerous moths, 

 both males and females, were confined in jars for several days and 

 fed on honey and water, but at no time was mating or oviposition 

 observed. 



The adults when disturbed fly rather quickly, but as a rule they are 

 to be found at rest on the underside of the leaves (PI. I, i; PI. II, c). 

 The eggs are usually deposited singly on the underside of the loaf (PI. 

 I, a) along the midrib or other veins, or in the angles formed by the 

 branching of the veins. The writer has found eggs scattered over 

 the grape canes, as has been recorded, and the finding of them on the 

 leaves has been corroborated by other observers. 



The young larvae, about one thirty-second of an inch in length 

 (fig. 2, &), emerge from the eggs in 8 or 10 days, and as they are unable 

 at this time to fold the leaves, search out a sheltered place among the 

 fohage, or even crawl into the folded shelter made by an older larva, 

 where they commence feeding upon the upper epidermis of the leaf. 



During its hfe the larva molts six times, the thoracic markings 

 becoming darker with each molt. During the periods of three or four 

 days between molts the larva feeds almost continuously, though it 

 is especially active at night. 



Wlien about two weeks old the larva makes a small fold in the leaf. 

 It commences the operation by spinning strands of silk from side to 

 side, across a portion of the leaf near the edge, each successive silken 

 strand being shortened until the edge of the leaf is gradually drawn 

 over and fastened with shorter bands of silk. It has been thought by 

 some investigators that among the leaf-tying and leaf-rolling larvse 

 the folding and fastening of the leaf is not so much the j)roduct of 

 actual strength exerted by the immature larva^ but is the result of 

 sohdification of the newly-produced silken strands in drying. Within 

 this shelter the larva spins a further protection, composed of many 

 recrossed strands of silk (fig. 3). If its shelter is torn open, the larva 

 wriggles violently and usually falls to tlio ground. 



I'hc attacks of a larva ar(5 not necessarily confined to a single leaf. 

 In rearing experiments conducted in jars two loaves usually consti- 



