770 REPORT UNITED STATES GEOLOGICAL SURVEY. 



The Striped Squash-Beetle, Dirtftroftca rittata Fabricius (Fig. 37).— Appearing on 

 the squash pumpkin, cucumber, and melon vines as soon as the leaves are up, eatiuo- 

 holes iu the leaves and killing the young plant ; a small yellow-striped beetle, whose 

 larva is a long, slender grub, which bores in the roots in June and July. 



This universal pest is so familiar iu the Northern States as to scarcely 

 need description. The beetle hibernates under leaves or in the crev- 



^rrr~n'~n~TT'n-r->^^ ^^^^ ^^ ^^^ bark of trees or iu 



/<V^P-LjJXUj^^^ fences, appearing among the 



^'^^ - " earliest insects of spring, at 



the time that the shad-bush 



{Amelanchier canadensis) is la 



blossom , on the pollen of whose 



r^^^. flowers it feeds, afterward de- 



^^ ^ '^^ serting wild flowers for the 



Fig. 37,— Striped Squash-Beetle; a, larva; &, garden. As SOOU as the seed- 



pupac, adult; rt, 12-spotted Deabrotica. leaves of the squash, pump- 

 kin, melon, or cucumber are formed, and even before they appear above 

 tlie surface of the soil, they devour them, and until the plant is about 

 six inches high it is liable to be devoured by them. I take the follow- 

 ing account in part from my " Guide to the Study of Insects." Dr. 

 H. Shimer has given an account of the habits of this insect in its 

 different stages. He states that the grub, in June and July, " eats 

 the bark and often perforates and hollows out the lower part of the 

 stem which is beneath the ground, and the upper portion of the root, 

 and occasionally, when the supply below fails, we find them in the vine 

 just above the ground." It hibernates in the pupa state. " The larva 

 arrives at maturity in about a month after the egg is laid ; it remains 

 in the pupa state about two weeks, and the beetle probably lives several 

 days before depositing her eggs, so that one generation is in existence 

 about two months, and we can only have two, never more than three, 

 broods in one season." Dr. Shimer has found them boring in the squash 

 and musk-melon vines as late as October 1. A generation appears in 

 two months, and there are two or three broods in a season. 



In an article in the American Naturalist (vol. v, p. 217), Dr. Shiii>er 

 gives further information concerning the habits of this beetle. The eggs, 

 he says, are deposited on the root at the surface of the ground, or on 

 the root just below the upper loose particles of earth, for although the 

 perfect beetle does not burrow into the compact ground, yet it often is 

 found down along the stem or root, just below the surface, under the 

 loose, dry clots or finer particles of earth which are not pressed closely 

 or beaten down by rains and hardened in drying. 



Descripiion of the larva. — It is along, slender, white, cylindrical grub, with a small, 

 brownish head. The prothorax is coreous. The thoracic legs are very slender, pale 

 brown ; the end of the body is suddenly truncated, with a small prop-leg beneath. 

 Above is an articular brown space, growing black posteriorly and ending in a pair of 

 upcurved, vertical, slender, black spines. It is 0.40 of an inch long. In its boring 

 habits, and its remarkably long, cylindrical, soft, white body this larva widely differs 

 from that of GaUenica, to which the beetle is closely allied. The j;«i)a is 0.17 of an inch 

 long, white, with the tij) of the abdomen ending in two long acute spines arising from 

 a common base. 



A Tachina parasite [Melanosliora diahroticce Shimer) preys upon this 

 beetle in the adult state, materially reducing its numbers. A single 

 maggot fills almost the entire cavity of the abdomen of its host, the 

 beetle. When about to transform into the pupa, the maggot leaves the 

 body of the fly, and its pupa-case is found in the surface of the ground, 

 the fly appearing late in July. 



