New York Agricultural Experiment Station. 549 



between the two surfaces. Thus they are feeding at this time as 

 leaf miners. Plate XL, tig. 2, is from a drawing, representing a 

 case-bearer feeding between the two surfaces of an apple leaf. 

 The case-bearers do not feed long as leaf miners, however, but 

 soon begin to eat olf the entire upper surface, leaving only the 

 frame work, as shown in Plate XL, fig. '^. The caterpillars grow 

 rapidly during this time and are soon strong enough to eat holes 

 clear through the leaves, avoiding only the midribs and larger 

 veins. 



Hoio the caterpillars cnhn-tjc their 'cases.— As stated on a previous 

 page, the caterpillars make their cases largely of woven silk. The 

 cases are just large enough during the winter to accommodate th<.' 

 young caterpillars, and thus it is necessary to enlarge them as the 

 occupants increase in size. This is done by extending the case 

 at the anterior end in the form of a tube of silk into which is 

 woven the pubescence from the leaf — frequently giving it a pink- 

 ish color or making it nearly pure white. . Very soon, however, 

 probably from the effects of exposure to the weather, the entire 

 case assumes a darker hue, resembling the bark in general color. 

 By May 6th the new portions of the cases equaled the old in aver- 

 age length. 



Habits of the caterpillars ichen attacking the flowers and full 

 grown leaves. — As soon as the flower buds begin to swell, the case- 

 bearers not infrequently attack these also, and the flowers them- 

 selves do not escape, as many were found last season with the 

 petals nearly eaten away by these intruders. When attacking 

 the flower buds, the caterpillars bore into them in much the same 

 manner as when attacking the leaf buds, as shown in Plate XL, 

 fig. 4, but when feeding in the full blown flower the petals may be 

 entirely consumed and frecjuently a considerable portion of the 

 pistil and stamens. Thus this insect not only injures the buds 

 and leaves, but, indirectly, destroys the fruit. Plate XL, fig. 5, is 

 from a photograph of two apple blossoms which have been in- 

 jured by the pistol-case-bearer. 



By the time the apple leaves are full grown the case-bearers 

 have reached their full size. At this time their cases measure, on 



