April, 1918] Parasites of Leaf-Hoppers 203 



as larvae until the following spring. A similar instance was 

 noticed by Perkins (1905) in the case of estivating larvas. 

 He says: "The number that remain as larvae, when others 

 emerge after the usual period, may amount to not less than 

 twenty-five per cent. " From two thousand cocoons of (Dryinus) 

 sent to Perkins in Hawaii from North America and arriving 

 there in November, two males emerged a few weeks after 

 arrival, and one male a month later. After being removed to a 

 cooler and damper place, both sexes issued in a short time. 

 This retarding of development is characteristic not only in 

 localities where winters are long and severe, but also where a 

 hot, dry period is experienced. It is a phenomenon that has 

 been noticed with other insects, and is a means probably of 

 insuring a continuance of the species in case the immediately 

 following generation is not successful and perishes for want of 

 food. 



DESCRIPTION OF STAGES. 



Egg. — The egg of the Gonatopits species studied (Figs. 8 and 

 9) is either oval or kidney-shaped, and varies in color from light 

 yellow to dark grey or dark brown. In length it averages from 

 .15-.211 mm. and in width from .08-. 095 mm. There is no 

 sculpturing on the chorion of any studied and in the case of 

 those laid within the body of the host, no surface structures. 

 In one egg, that of a Gonatopus species on Deltocephaliis inimicus 

 nymphs, a circular ridge, hardily visible, was noticed at one 

 pole, and a black excrescence about half way down on one side. 

 When laid on, or partly exposed on, the cuticula of the host 

 it may be of the same color and almost invisible, as in Gonatopus 

 contort uhis Patton, or its color may be sharply contrasted with 

 that of the host. 



Larva : First instar. — The earliest stage found was that of 

 a larva within its egg shell ready to hatch (Fig. 10). It was 

 structureless, with no visible appendages or segments. A small 

 dark brown spot present at one extremity might serve for the 

 purpose of breaking open the egg chorion, which is comparatively 

 hard and thick. 



Second instar. — The second instar of Aphelopus comesi n. sp. 

 was studied, (Fig. 11). The specimen observed measured 

 .54 mm. in length and .23 mm. at its greatest breadth near 

 the head region. 



