238 



INTERNATIONAL CONGRESS OF VITICULTURE 



insect is apt to be only locally abundant within the area of its known 

 distribution. It has been noticed frequently that grapes in one locality may 

 suffer greatly every year while in other localities, not far distant, injury will 

 scarcely be noticeable. Probably the presence or absence in a given locality 

 of wild grapes, in which the curculios breed, has much to do with this 

 irregularity in the distribution of the pest. 



LIFE HISTORY. 

 The Egg and Oviposition. 



In the latitude of central West Virginia the adult grape curculio, which 

 is a small, brown, inconspicuous beetle, appears in the spring upon the foliage 

 of grape vines, usually during the latter part of the month of May. The time 

 the beetles first make their appearance corresponds rather closely with the 

 blooming of the grape. Late in June, when Concord grapes are about one- 

 fourth grown, the beetles begin to oviposit in the fruit. 



The egg is oval in shape, its dimensions being about .015 by .022 inch. 

 The color is translucent white changing to yellowish as incubation advances. 



In depositing her eggs the female makes use of her slender snout, upon 

 the point of which the mouth is situated, to form a small opening in the skin 

 of the fruit. She then eats out a cavity in the pulp, about one-tenth of an 

 inch in diameter, and deposits within it a single egg. She then seals the 

 small opening in the skin with a pellet of excrement, evidently for the pur- 

 pose of securing the egg against natural enemies. The point where the egg 

 is deposited shows as a discolored and slightly depressed spot on the skin 

 of the fruit. The spots have a characteristic appearance and often furnish 

 the vineyardist with his first intimation that the insect is present on his 

 vines. In occasional cases where the eggs fail to hatch a hard tissue forms 

 around the egg-cavity so that the punctured fruit is worthless whether or 

 not the larva develops. 



iiil 



Fig. 1. 



Egg puncture of grape curculio. Two left, punctured, 

 uninjured. 



Two right, 



The females deposit on an average something over 250 eggs each, and, 

 until all available grapes are occupied, the beetle will usually select a sound 

 fruit for each egg. The egg-laying period begins late in June and continues 

 for about eighty days. A single female may deposit as many as fourteen 

 eggs in a single day. The eggs deposited at the beginning of the season 



