TWO LEAFHOPPERS INJURIOUS TO APPLE NURSERY STOCK. 9 



Forbes and Hart (10) in 1900 mentioned the occurrence of four 

 or more generations in Illinois. In 1908 Washburn (15) suggested 

 that there were two and possibly three generations in Minnesota. 

 R. L. Webster (18) in 1910 recorded four generations at Ames, Iowa. 

 E. H. Gibson, of the Bureau of Entomology, has noted as many as 

 five generations in southern Missouri, and six in southern Mississippi. 



The Egg. 



The eggs are laid singly in the sides of the mid-vein and occasionally 

 in the smaller veins of the terminal leaves. They are deposited in 

 pockets just under the epidermis, usually lying in a longitudinal 

 position. It is very difficult to locate the eggs as they are the same 

 color as the tissue in which they are embedded, while the epidermis 

 under which they are hidden is covered by the pubescence of the leaf. 

 When the pubescence is removed, the tissue covering the egg appears 

 slightly distorted and eventually becomes discolored. In making 

 dissections of the leaf tissue the delicate egg is often crushed, where- 

 upon the egg contents may be mistaken for the plant juice in the vein. 

 When ready to hatch, the immature nymph pushes its head through 

 the anterior end of the eggshell and forces a tiny hole in the thin 

 epidermal leaf-covering, slowly drawing its body free from the 

 enveloping tissue. 



Eggs of Empoasca mail have been found in the leaves of the follow- 

 ing host plants: Apple, pear, peach, plum, cherry, quince, alfalfa, 

 beet, and potato. 



Adults of all three generations deposit summer eggs in leaves in 

 the manner mentioned above. Washburn (15) stated in 1908 that 

 the last-brood adults of this species deposit winter eggs under the 

 bark of nursery apple trees in Minnesota, and that the nymphs hatch- 

 ing therefrom the following spring attack the lower leaves of the trees. 

 Webster (18) in 1910 made similar observations in Iowa. At West 

 Chester, Pa., the apple leafhopper certainly does not pass the winter 

 in the egg stage. Several experiments were made in the attempt to 

 obtain winter eggs by confining numerous pairs of third-brood adults 

 in cages, but all proved unsuccessful. Field observations for two 

 seasons on several thousand trees also substantiate the above view. 

 However, winter eggs of the rose leafhopper (which will be treated 

 later) were found in abundance in this locality, the nymphs of which 

 confine their feeding to the lower leaves of the trees. 



The Nymph. 



The newly-hatched nymphs are very small, wingless, white in color, 

 and of the same form as the adults. Immediately after hatching they 

 settle down to feed, inserting their minute beaks in the leaf tissue 

 and sucking the plant juices. A day or two after taking food into 



132816°— 19 2 



