4 BULLETIN 730, U. S. DEPARTMENT OF AGRICULTURE. 



the "pigeon'' grape (V. aestivalis), and the "frost" grape (V. cordi- 

 foUa). Under similar conditions one variety of cultivated grape will 

 suffer about equally with another. Frequently a discrimination will 

 seem to be shown by the curculio between varieties, since the fruit 

 of one vine may be attacked more extensively than that of another 

 in the same locality. Such discrimination, however, is usually due 

 to the particular locations of the vines rather than to any varietal 

 peculiarities. The fruit of vines trained on the side of a house or 

 of those growing in isolated positions in a field will escape injury 

 to a far greater extent than will that of groups of vines trained on 

 wire, fence, or trellis. Of the wild species the fox grape suffers 

 about equally with the cultivated varieties, the "pigeon" grape to a 

 less extent, and the "frost" grape is very rarely attacked. The 

 immunity from attack of this last species is probably due to its 

 small size and to the fact that it develops much later in the season 

 than do the other species. 



THE LIFE CYCLE IN BRIEF. 



The beetles appear upon grape foliage in the spring and feed for 

 ten days or two weeks on the upper epidermis and parenchyma of 

 the leaf before beginning to deposit eggs within the young fruit. 

 The larvae (PI. I, H) from the eggs feed upon the pulp and seeds 

 of the fruit until full grown when they leave their feeding place and 

 pupate within pellet-like earthen cocoons (PL I, J) located at or 

 just beneath the surface of the ground. In about three weeks the 

 beetles issue from the cocoons and go to the grape foliage, where 

 they feed rather freely on the upper surface of the grape leaves until 

 cool weather in the fall drives them into hibernation. 



A few relatively unimportant departures from the foregoing rule 

 are recounted later in this paper. 



DESCRIPTION. 



THE EGG. 



The eggs (PL I, E, F) are rather uniformly oblong elliptical in 

 shape. The surface is smooth and opaque, white when first depos- 

 ited, but turning to yellowish on the second and third days. The 

 average measurement of 10 specimens was 0.46 by 0.71 mm. The 

 egg is attached to the wall of a roomy cavity which the female beetle 

 with her snout excavates from the pulp of the grape through a small 

 hole made in the skin. 



THE LARVA. 



The legless, fusiform, curved larva (PL I, H; PL II, F) is white with 

 light brown head, the body usually being clouded with the dark-colored 

 contents of the alimentary canal. The average length is 7 mm. and 



