ARTICULATA. 187 



being very different from that of C. septeridecim. The body is robust, the 

 head large and triangular, with three stemmata, the eyes prominent, the 

 antenniiB short and thin, with six articulations, and the wings are large, and 

 generally transparent. 



The history of Cicada septendecim^ known in the United States as the 

 seventeen year locust^ has been given in a valuable pamphlet by Dr. Potter, 

 of Baltimore, who, deceived by the popular name, fancied that anything 

 called locust must belong to the genus Locusta^ and he accordingly names 

 the insect Locustct SejytentrionaUs AmericayicE deceni septima^ confounding 

 these hemiptera with the grasshoppers, and naming the latter Cicada. 

 Yernacular names being entirely independent of the scientific ones, 

 attempts to make them correspond generally result in confusion. Dr. 

 Harris gives some useful details in his Injurious Insects of Massachusetts, 

 and Dr. S. P. Ilildreth has written upon it in Silliman's Journal, vol. xviii. 

 p. 47, and 2d Series, vol. iii. p. 216. See also vol. xiii. p. 221. The pupa of 

 this insect leaves the ground in tlie Southern States in February and March, 

 in Pennsylvania in May, and in Massachusetts in June. The female cuts 

 openings with her ovipositor in the tender branches of trees, where her 

 eggs are inserted ; this causes the branches to die, and one observer relates 

 an instance in which " the tops of the forests for upwards of a hundred 

 miles appeared as if scorched by fire." It requires fifty-two days for the 

 young to hatch, when they immediately precipitate themselv'es to the 

 ground, which they enter and attack the roots, the juices of which they 

 suck. Miss M. A. Morris (Proceed. Acad. Xat. Sci., vol. iv. pp. 132 and 

 190) has ascertained that these larvae do much damage to fruit trees by 

 their attacks upon the roots. She found them in great numbers upon all 

 the roots which were more than six inches beneath the surface, and the 

 trees were evidently suffering under their attacks. The larvse were firmly 

 attached to the roots by the insertion of their rostrum, and inclosed in a 

 compact cell of clay without outlet, rendering it probable that they are 

 sedentary where they first attach themselves. According to Miss Morris, 

 they are destroyed by moles. The anterior feet of the larva and pupa are 

 robust and adapted for digging, but those of the imago do not exhibit this 

 character. 



Fam. 8. Notonectidce {pi. 80, Jigs. 72, 73). This family of small preda- 

 ceous insects is named from the habit which the species have of swimming 

 with the back below. They are aquatic, the head and eyes are large, 

 the antennas small, with four articulations, and the posterior feet are long 

 and fringed, held out in repose like a pair of oars, and used like them in 

 swimming. They are able to fly from one piece of water to another. 

 Corixa striata {pi. 80., fig. 72 a I)); Notonecta glauca {fig. 73). 



Fam. 9. Nepidce {pi. SO, figs. 68-71). This family is predaceoua and 

 aquatic, the species living at the bottom of quiet waters. The body is 

 generally depressed, the antennte about as long as the head, and inserted 

 below the eyes so as to be hidden. The tarsi are dimerous, and the 

 anterior feet raptorial. Ranatra linearis {fig. 68) ; Wepa cinerea {fig. 

 69) ; JSfaiicoris dmicoides {fig. 70) ; Belostoraa {fig. 71). The last genus 



391 



