SPEAYING AGAINST THE GRAPE LEAFHOPPER. 



Fig. 2. — The grape 

 leafhopper : 

 Nymph of the first 

 rnolt. Greatly 

 enlarged. (Origi- 

 nal.) 



warm afternoons of early autumn the air will be filled with thousands 

 of these little creatures drifting somewhat aimlessly on the light 

 breeze and causing considerable annoyance by get- 

 ting into the eyes, ears, and mouth of the beholder. 

 A close observation of the underside of the leaves 

 of grapevines at this season is likely to reveal the 

 immature or nymphal stage of the insect (fig. 2). 

 These vary greatly in size, from those just hatched 

 to the full-grown nymphs with well-developed wing- 

 pads (fig. 3) , but they have always the same general 

 form. These leafhoppers belong to the same order 

 of insects as do the scale insects and the plant-lice 

 and secure their food by sucking the juices from the 

 plant in much the same manner as the mosquito sucks blood from an 

 animal. A knowledge of this method of taking food is of the great- 

 est importance from an economic standpoint, since insects which take 

 their food in this way are usually amenable to a spray application of 



an entirely different quality from that which 

 is used in the case of insects which chew or 

 masticate their food. Sucking insects are 

 usually combated by the use of some caustic 

 or smothering substance which must come in 

 direct contact with the outside of the body 

 of each individual, practically at the time 

 of application and in sufficient quantity and 

 strength to effect its almost immediate de- 

 struction; whereas, in the case of the chew- 

 ing insect a stomach poison must be applied, 

 not to the body of the insect, but to the sur- 

 face of that portion of the plant or fruit 

 upon which the insect feeds. 



The adults and the nymphs of the grape 

 leafhopper feed upon the underside of the 

 grape leaf and by sucking the juices there- 

 from cause it to take on a yellowish, mottled appearance (fig. 4), 

 which later turns brown, and where the infestation is heavy the leaves 

 dry out and become functionless before the fruit is mature. (See 

 fig. 5.) 



LIFE HISTORY. 



Fig. 3. — The grape leafhop- 

 per : Fully developed 

 nymph of the fifth molt. 

 Greatly enlarged. (Origi- 

 nal.) 



HIBERNATION 



The grape leafhoppers pass the winter as winged adults, which 

 migrate from the vines during October. By the time the grapes are 

 harvested only a small percentage of the adults will be found upon 



