1923 



ENTOMOLOGICAL SOCIETY. 



53 



wide. Same as second instar except the thoracic colour markings more pro- 

 nounced, and the wing pads extend beyond the first abdominal segment. 



Fourth Instar. Size 1.98 mm. to 2.16 mm. long, by .54 mm. to .72 mm. 

 wide. Same as second instar except wing pads extend to posterior margin of 

 second abdominal segment. 



Fifth Instar. Size 2.61 mm. to 2.70 mm. long, by .72 mm. to .81 mm. 

 wide. Same as second instar except wing pads extend to the fourth abdominal 

 segment. 



Emergence from Eggs. When hatching occurs the shell of the egg and 

 the leaf epidermis are ruptured, and the soft, round, glossy nymphal head begins 

 to appear slowly — oozing out as it were, like a globule of sap. The nymph 

 gradually wriggles its way out; the appendages which are folded beneath the 

 body slowly become free, and the nymph walks off with a wobbling gait. 



Recently hatched leaf hopper nymphs on grape leaf (natural size) . 



Habits. The nymph inserts its mouth parts into the leaf tissues and 

 commences to imbibe the plant juices an hour or two after it emerges from the 

 leaf; and it continues to feed throughout its entire life except when moulting 

 or when disturbed. It feeds altogether on the underside of the leaf, preferably 

 alongside a vein or in the junction of two veins; but under crowded conditions 

 it will insert its proboscis anywhere on the lower leaf surface. 



Ordinarily the nymph will remain until reaching maturity on the leaf on 

 which it was hatched out. It was commonly observed in the insectary that, 

 even on the plants with fresh uninfested leaves, a small colony of nymphs would 

 remain on one leaf until they reached the adult stage. On badly infested vines, 

 however, the nymphs undoubtedly migrate to some extent. In making observa- 

 tions on the hatching of the eggs, it was frequently observed that leaves from 

 which all nymphs had been removed became infested overnight with a few third, 

 fourth and fifth instar nymphs. 



