INSECTS INJURIOUS TO THE GRAPE 499 



wings being brown and the hind-wings transparent and bordered 

 with brown. The posterior margins of the second and fourth 

 abdominal segments are orange or lemon-yellow, and there are 

 spots of the same color at the bases of the wings. The males 

 are considerably smaller than the females. The moths fly during 

 the day and are readily mistaken for wasps of the genus Polistes. 

 The males fly in a quick, wasp-like manner, and when they rest 

 on a leaf will occasionally flutter the wings like an angry wasp, 

 which is accompanied by a low buzzing sound, which makes the 

 mimicry very effective. 



Life History. The eggs are laid singly on weeds, grasses or 

 other vegetation in the vineyard or on the bark or leaves of the 

 vines, a single female laying some 400 eggs. 

 The egg is oval, one-twenty-fifth inch long, 

 of chocolate-brown color, and finely pitted 

 and sculptured. They are very readily washed 

 off by the rain and drop to the soil, where 

 they hatch in about three weeks. The little 

 larvae bore directly into the soil, wherever 



they may be, in search of grape roots, and FIG. 358. Egg of 



may survive for several days without any grapevine root- 

 food. Upon reaching a root the larva bores 



greatly enlarged. 



through the outer bark and then makes an (After Brooks.) 

 irregular burrow in the softer parts of the 

 bark, which may encircle the root several times. As the bur- 

 rows grow larger they run with the grain of the wood, and as 

 they are enlarged with the growth of the larva, only the outer 

 bark is left on roots of one-half inch or less in diameter, the interior 

 being tunnelled out and filled with the castings of the larva. Most 

 of the larvae feed a foot or so from the base of the vine, though one 

 was found on a root nine feet from the base. The Iarva3 bore in the 

 roots until the second fall, when they are about full grown and 

 make cells or hibernacula, thinly lined with silk, in which they 

 hibernate in the root. The larva becomes full grown the next 

 spring and is then 1^ to If inches long, of the general shape 

 shown in Fig. 359, yellowish-white, with a small brown head, three 



