186 



UNIVERSITY OF CALIFORNIA EXPERIMENT STATION. 



THE EGG. 



Description and Appearance. The eggs of the grape leaf-hopper are 

 very minute objects about three hundredths of an inch long and about 

 one third as wide. They are slightly bean-shaped, as shown in figures 

 8 and 9. As they are situated naturally in the leaf, within the tissues, 

 they are difficult to detect unless one is familiar with their appearance. 

 If the light is at the right angle the epidermis will be seen to be raised 

 and slightly more transparent than the surrounding tissue, and the 

 form of the egg distinguished beneath. We occasionally met growers who 



claimed to have observed 

 the eggs on the underside 

 of the leaf ; 'but they were 

 mistaken in thinking that 

 little transparent droplets 

 of sap were the eggs of the 

 hopper. These are exuda- 

 tions of sap which usually 

 occur along the larger 

 veins, and do resemble 

 somewhat an insect egg. 

 The outer surface of these 

 droplets of sap soon hard- 

 ens or becomes viscid on 

 exposure to the air, thus 

 resembling the shell of an 

 egg and making the simi- 

 larity more complete. 



Fig. 8. The egg of the grape leaf-hopper photo- 

 graphed in its natural position within the tissues 

 of the leaf. The circular spot at the top repre- 

 sents the eye of the developing nymph within. 

 Greatly enlarged. 



Where Laid, Harris, 1 

 in 1841, stated that the 

 eggs of the hopper were 

 laid on the leaves, but this 

 statement appears not to have been substantiated by actual observation. 

 Townsend 2 in 1891 supposed that the drops of sap, mentioned above, 

 represented the egg punctures of these insects, but this is now known 

 to be erroneous. Marlatt 3 in 1895 stated that "the eggs are thrust by 

 the female singly into the substance of the leaf on the lower side, either 

 into the midribs and large veins or in the intervening spaces." Photo- 

 graphs were taken of the eggs in the leaf in 1898 by Professor Wood- 

 worth of this station, and these are still on file here. The first complete 



1 Insects Injurious to Vegetation, Flint Ed., p. 228. 



2 Bulletin No. 3, N. M. Agr. Exp. Sta. 



3 U. S. D. A. Yearbook, 1895, p. 402. 



