220 THE GRAPE 



INSECTS OF THE GRAPE. 



Grape Phylloxera. — The grape phylloxera is an insect native 

 to the United States, and at times has severely threatened 

 the grape industry in the Pacific coast regions. This insect 

 is a small plant louse, and its life history is very complicated, 

 involving four different forms of aphids. The four forms 

 may be briefly enumerated as (1) the root form, (2) the leaf 

 gall form, (3) the winged form and (4) the sexual form. The 

 root form is the most destructive, and the gall form is also 

 very injurious. 



The principal means of control lies in the selection of resist- 

 ant vines. Since the most destructive form of this insect is 

 found on the roots, which are protected in such a way that no 

 spray can be used, it becomes necessary to employ some other 

 means of control. Carbon bisulphide, which is a volatile 

 gas, heavier than air, has been extensively used. This 

 material is the most effective on light soils but does not lend 

 itself to very successful use on heavy clay soils. It is also 

 relatively expensive. Carbon bisulphide may be applied at 

 any time other than during the blooming and the ripening 

 season. Two applications usually give the best results. To 

 apply the material pour one-half of an ounce into a hole 

 about 1 foot in depth and not closer than 1 foot from the vine. 



If water is available for irrigation it offers one of the best 

 means of control for this insect, which is done by flooding 

 the ground to a depth of about 6 inches and allowing the 

 water to remain on the soil for about ten days. The best 

 results are obtained by applying the water so soon as the 

 vines cease active growth in the fall. 



Flea Beetle. — The flea beetle is a little insect which often 

 becomes serious on the grape. It is a bluish-green beetle, and 

 the chief damage it does is to eat the buds about the time they 

 begin to swell in the spring. If the beetles are very abundant 

 they often destroy all of the buds, which greatly retard the 

 leafing out and in severe cases of infestation sometimes kill 

 the vine. The larva? of the insect hatch from the eggs about 

 the time the leaves are expanding and at once attacks them, 

 eating out irregular holes. 



