123 



a row of six small, black, nearly equal dots along the front of the head, 

 as seen from above, and the face is barred with black. Cicadula sexno- 

 tata (Fig. 113) has a pair of black dots at the back of the upper surface 

 of the head, and in front of each of these a pair of short black cross-bars. 

 The apple leaf-hopper (Fig. 114) is rather translucent green, with six 

 white spots along the front edge of the pro thorax. 



These leaf-hoi)pers injure vegetation by inserting a tiny beak and 

 sucking out the sap. Mimite whitish or yellowish dots usually appear 

 at these punctures, which sometimes become numerous enough to 

 whiten the whole leaf. The growth of the plant is of course checked 

 to a corres[)onding degree. The eggs are usually inserted imder the 

 epidermis of leaves or of soft stems, miiuitc elevations of the surface 

 being thus made. 



Tlic fiv(! species differ gn.'atly in life; history. A(/allta is singlc-broodctl 

 and winters partly grown. Th(; eggs are laid by the middle of July. 

 The other s[)ecies probably winter in the egg stage, like most leaf-hoppers. 

 At any rate, neither adults nor young have ever been found by us in 

 extensive winter collections. Deltocepfmlus and Cicdduht, are double- 

 brooded. The eggs of J), inimicus hatch early in May in grass lands, 

 and the adults are abundant from the first of June to the middle of July. 

 A second })rood of adults begins to appear the middle of August. 

 D. nif/rifrons and Cicadula scxnotala have a similar life history. Empo- 

 asca vi(Ui matun^s mf)re rapidly, completing its growth from the egg 

 within a month. There are probably four or five; broods in a season, 

 the first becoming adult in late April 

 or early May. 



All th(^s(! species are widely dis- 

 tributed, A(/aUia (juadripunctata and 

 Cicadula scxnotata being more distinctly 

 northern in their I'aiige than the 

 others. 



TUK (X)RN r.FAF-LOUSM 



Aphis maidis Fitch. 



In the latter part of the summer 

 this bluish green i)lant-l()use may 

 occasionally be found on the younger 

 leaves, the tassel, and upper par-t of 

 the stalks of corn, and more abun- 

 dantly and frecjuently on broom-corn 

 and sorghum. Multiplying in place by 

 the birth of living young, which do 



Fi<;. 11.5. 



The Corn Leaf-loiuse, Aphis 



niaidis, v/xuhWhh female, greatly eiilarEed, 



, 1 (■ , I • 1 c ■ • with aiiteiiiia and tip of abdomen more 



not wander from their place of origin, enlarged. 



