676 



of Natural 



hoppers, as they may be called, inhabit the 

 foreign and the native grape-vines, on the 

 under surface of the leaves of which they 

 may be found during the greater part of the 

 summer ; for they pass through all their 

 changes on the vines. They make their 

 first appearance on the leaves in June, when 

 they are very small and not provided with 

 wings, being then in the larva state. During 

 most of the time they remain perfectly quiet, 

 with their beaks thrust into the leaves, from 

 which they derive their nourishment by suc- 

 tion. If disturbed, however, they leap from 

 one leaf to another with great agility. As 

 they increase in size they have occasion fre- 

 quently to change their skins ; and great 

 numbers of their empty cast-skins, of a white 

 colour, will be found, throughout the sum- 

 mer, adhering to the under sides of the 

 leaves, and upon the ground beneath the 

 vines. When arrived at maturity, which 

 generally occurs during the month of August, 

 they are still more agile than before, making 

 use of their delicate wings as well as their 

 legs in their motions from place to place ; 

 and, when the leaves are agitated, they leap 

 and fly from them in swarms, but soon alight 

 and begin again their destructive operations. 

 The infested leaves at length become yel- 

 low, sickly, and prematurely dry, and give 

 to the vine at Midsummer the aspect it na- 

 turally assumes on the approach of winter. 

 But this is not the only injury arising from 

 the exhausting punctures of the vine-hop- 

 pers ; the plant languishes, and, if the evil 

 be allowed to go on unchecked, in a few 

 years the vines become exhausted, barren, 

 and worthless. In the autumn the vine- 

 hoppers desert the vines, and retire for 

 shelter during the coming winter beneath 

 fallen leaves and among the decayed tufts 

 and roots of grass, where they remain till 

 the following spring, when they emerge from 

 their winter quarters, and in due time de- 

 j posit their eggs upon the leaves of the vine, 

 and then perish. 



THALARCTOS. [See BEAK, POLAR.] 



THALASSIDROMA. A genus of web- 

 footed Birds closely allied to Procellaria, 

 and commonly called Stormy Petrel, under 

 I which word, two or three species are de- 

 scribed. We may here describe another 

 oceanic species, the 



THALASSIDROMA LEUCOOASTER, or 



I WlIlTE-BET.LIED STORMY PETREL. This IS 



a fine and powerful species of the Petrel 

 family of birds ; easily distinguished from 

 all others by the total absence of black down 

 the centre of the abdomen, and the short- 

 ness of its toes. It is seen (says Mr. Gould) 

 fluttering over the glassy surface of the 

 ocean during calms with an easy butterfly- 

 like motion of the wings, and buffeting 

 with equal vigour the crests of the loftiest 

 waves of the storm ; at one moment descend- 

 into their deep troughs, and at the next 

 rising with the utmost alertness to their 

 highest points, apparently from an impulse 

 communicated as much by striking the sur- 

 face of the water with its webbed feet, as by 

 the action of the wings. The head and neck 



is of a deep sooty black ; back grayish 

 black, each feather margined with white ; 

 wings and tail black ; chest, all the under 

 surface, and the upper tail-coverts, white ; 

 bill and feet jet-black. Like the other 

 members of the genus, it feeds on mollusca, 

 the spawn of fish, and any kind of fatty 

 matter that may be, floating on the surface 

 of the ocean. [See PETREL.] 



THECL A. A genus of diurnal Lepidop- 

 tera, abounding in exotic species, but of 

 which only six or seven are met with in this 

 country. They are called by collectors 

 " Hair-streaks," from the under-side of the 

 wings being frequently ornamented with 

 two or three delicate, straight, or zigzag pale 

 lines on a dark ground. We particularize 



The THECL A QUERCUS, or PUKPLE 

 HAIR-STREAK BUTTERFLY. About the mid- 

 dle of July this species of the Papiliona- 

 ceous tribe is seen frequenting the tops of 

 lofty oaks and ash trees. Its wings are 

 dusky black above : the male with the disc 

 of the anterior deep glossy blue, formed of 

 an oblong patch, and extending towards 

 the anal angle ; the female with the entire 

 disc purple, and a dusky margin : beneath, 



w 



PORPLE HAIR-STREAK BOTTERFT.T. 

 (THECLA QOERCDS,) 



both sexes are similar ; the anterior wings 

 are cinereous, with a short white streak 

 on the costa towards the apex ; between 

 which and the posterior margin the wing 

 is paler, witli a few whitish spots : the pos- 

 terior wings are similar at the base, and 

 have an undulated white streak, slightly 

 edged internally with dusky ; beyond this 

 are two rows of whitish crescents, with a 



fulvous spot at the anal angle. Body black 

 above, cinereous beneath ; tail black ; an- 

 tennae black, faintly annulated with cine- 

 reous. The purple blotch on the anterior 

 wings of the male varies greatly in size ; and 

 the wings of the female are sometimes only 

 slightly purpurescent. Caterpillar lightish 

 brown, with three rows of green dots ; it 

 feeds on the oak. Chrysalis rust-coloured, 

 with three rows of brown dots. 



