82 



DECIDUOUS FRUIT INSECTS AND INSECTICIDES. 



tubercles, with bristles similar to those in the preceding instar, 

 0.2-0.25 nnn. in length, with the black on the apices, joints, and bulbs 

 at the base more ^Dronounced, causing the tubercles to appear black to 

 the naked eye. All the segments laterally, and dorsum of the an- 

 terior and posterior segments with long, segmented, whitish hairs 

 variable in length. Thoracic feet small, pointed, dilute-brown, 

 darker at the tip ; abdominal feet larger, apex with a circlet of black 

 bristles, all the feet similar in color to the rest of the body. Length, 

 3.5-4.5 mm.; width of head, O.GGG mm. (nearly constant). 



Fourth instar. — Body sulphur-yellow, head retractile, dilute-brown, 

 darker on exposed portion, mandibles and eyes brownish-black. 



Head when viewed from above oval- 

 pyramidal in form. Tubercular areas 

 very prominent now to naked eye, 

 appearing as black, bristly, wartlike 

 patches, this appearance due to the 

 black tips of the whitish, jointed bris- 

 tles; joints and bulbs at base of bristles 

 blackish. Tubercular areas on dorsum 

 of segments 7, 8, 9, and more especially 

 7 and 9, fainter to naked eye than on 

 other segments, as the bristles are not 

 so heavily tipped with black nor are 

 the joints black. Dorsum of anterior 

 and posterior segments and all segments 

 laterally with long, whitish, segmented 

 hairs of variable length. Thoracic and 

 abdominal feet yellowish, longer, but 

 marked the same as in the third instar. 

 Length, 7-8 mm. ; width of head, 1.05- 

 1.06 mm. (nearly constant). 



Fifth imtar. — Body deep sulphur- 

 yellow, head retractile, dilute-brown, 

 darker on exposed portion, mandibles and eyes brownish-black. 

 Shape of head similar to that in the fourth instar. Tubercular 

 areas now very prominent to naked eye and appearing as black, 

 bristly, wartlike patches. Bristles under g-inch objective same as in 

 the fourth instar, but more distinct and longer (0.20-0.33) nnn. in 

 length). Tubercular areas distinct on all segments, and to naked eye 

 with a slight opaque-bluish cast. Dorsum of anterior and posterior 

 segments, and all segments laterally, with long, segmented, ^^hitish 

 hairs, longer than in fourth instar. Thoracic feet yellow, tipped with 

 black ; abdominal feet yellow, Avith a terminal circle of black bristles. 

 Length, 8-10 mm.; width of head, 1.15-1.45 nun. (variable). 



Fig. 14. — The grape-leaf skeleton- 

 izer {Huiriifina amerlcana) : 

 Full-grown larva, at left ; a, lat- 

 eral view of head and protho- 

 racic segments ; b, lateral view 

 of posterior segments. En- 

 larged. (Original.) 



