BUGS. 239 



It varies greatly in size, the small specimens being only a little more than an inch 

 in width across the spread wing-covers, while the large ones measure fully an inch and 

 a half at the same place. A variety has the wing-covers almost covered by the black 

 dots, and these sometimes run together in the form of large spots. The common type 

 closely resembles moths of the group of arctians, and this one especially imitates the 

 colors, markings, and somewhat the form of Spilosom.a cunea. It inhabits the tropics 

 of Brazil, being common in various places pear Para, Bahia, and Rio de Janeiro. 

 There, in the midst of the splendors of vegetation, it dwells upon the branches of 

 various creeping plants, and at times conceals itself from the attempts of pursuing 

 birds by hiding in the bunches of orchid flowers which hang ever ready for its pro- 

 tection. 



The sub-family Achilida is composed of neat, medium-sized or small insects, some- 

 what parallel-sided, which have the wing-covers opaque and often mottled, or marked 

 with branching figures, or banded with bright colors. The head is narrow, and either 

 blunt or a little produced, the body rather depressed, and the fore-thighs, trochanters, 

 and shanks are of about equal length, while the hind-shanks are either unarmed, or 

 furnished with one or three spines on the outer margin. On the tip of the latter a pair 

 of exceptionally thick and large denticulated spurs occupies the sides of the notch 

 into which the tarsi are set. 



The beautiful Plectoderes collaris belongs here, and forms an agreeable offset to the 

 more sober-colored species in the midst of which it is placed. 



It is a coal-black insect, with a bright orange band upon the back part of the meso- 

 thorax which passes forward to and crosses the face. The head is more than normally 

 wide, but is not as wide as the prothorax, unless the very large, prominent eyes are 

 counted in the measurement. Three carinate, longitudinal lines occupy the disc of 

 the mesothorax, and the prothorax is a mere sinuated collar. A short yellow stripe is 

 often present upon the costal areole, and the disc is sometimes marked with short, 

 remote orange streaks. It is about one-fourth of an inch in length to the tip of wing- 

 covers ; and it lives on low bushes near watercourses in the province of Para, as well 

 as in other parts of the Amazonian basin. 



North America shares with Europe the interesting genus Helicoptera. In the 

 foi-mer country, however, it is not confined to the warmer parts of the continent, but 

 lives with equal freedom in the ancient forest region of Lake Athabasca, in the pine 

 barrens of Georgia, or upon the almost sterile plateau of San Diego, California. 

 Wherever a solitary pine-tree can find place to thrust its roots into 

 the hard soil, there the Helicoptera settles and brings up its nu- 

 merous progeny. These insects have more of the form of a feather 

 fan than the preceding, having the narrow, produced, and generally 

 triangular head in the place of the handle. 



The species first discovered in this country was Helicoptera opaca. 

 This species is of a soot-black color above, closely dotted with pale 

 atoms, has a pale yellow spot on the costal border near the tip of 

 the wing-covers, while a broad, orange band crosses the face and ex- 

 tends upon the sides of the chest. A small yellow spot also covers 

 the tip of the scutellum. The head forms a blunt triangle as seen ^'<*- ^''*^^-'^'="'"'^- 

 from above, has the side edges turned up, and a grooved middle 

 line bounded each side by keeled edges. It measures from apex of head to tip of the 

 wing-covers rather more than one-third of an inch. At first only a few specimens, col- 



