TIME WHEN WINGS ARE ACQUIRED. 237 



^'The two species wbicb are most often thus found with the young 

 locusts, and supposed from their size and conspicuousness to be guides, 

 are the American Acridium {Acridium Americanum Drury, Fig. G), 

 and the Ooral-wiuged lio- 

 cust{(Edipodaph(€nicoptera 

 Germ., Fig. 7). The former 

 is our largest and most ele- 

 gant locust, the prevailing 

 color being dark brown, 

 with a broad, pale-yellow- 

 ish line along the middle of ^^^ i.-co^^,..^,^^^ locust. (Aiier Eiiey.) 

 the back when the wings 

 are closed. The rest of the body is marked with deep brown, verging to 

 black, with pale reddish-brown, and with whitish or greenish yellow; 

 the front wings being prettily mottled, the hind wiugs very faintly 

 greenish, with brown veins, and the hind shanks generally coral-red with 

 black-tipped, white spines. The species is quite variable in color, size, 

 and marks, and several of the varieties have been described as distinct 

 species. The coral- winged locust is also an elegant species, the colors 

 being brown-black, brick-yellow inclining to brown, and a still paler, 

 whitish gray ; the hind win^s varying from vermilion-red to pink, with 

 more or less yellowish-green, and with a broad external dusky border, 

 broadest and palest at tip. The hind shanks are yellow, with black- 

 tipped spines. This species is also quite variable." 



TIME OF YEAR WHEN WINGS ARE ACQUIRED. 



The time elapsing between birth and the acquirement of full wings 

 varies accordin g to season and weather; cold, wet weath er retardin g, warm , 

 dry weather accelerating development. At Saint Louis, in an inclosure 

 outdoors, we have obtained the mature insect in 72 days from hatching, 

 and the first pupal or fourth stage in 29 days from hatching, indoors. 

 Mr. Whitman, from a single experiment made in 1877, found that ex- 

 actly 60 days elapsed from birth to maturity, in confinement. In South- 

 ern Texas, in 1877, the locusts began to fly by the middle of April; from 

 South Iowa northward, from the middle of May to the middle of July. 

 The average period, at Saint Louis, between hatching and maturity, of 

 C. femur-rubrum, we have found to be 70 days ; of C. atlanis, 80 days; 

 of Acridium Americanum, 70 days. In 1875, when the hatching and de- 

 velopnaeut of spretus were more regular and normal than in 1877, the 

 interval was from 42 to 60 days, and we may put the average interval, 

 under favorable conditions, at 50 days. By adding these 50 days to 

 the time given {ante, p. — ), when the bulk of the insects hatch in differ- 

 ent latitudes, we get the time of year when the great body of them will 

 acquire wiugs, and by allowing 5 days more for the migrating propensity 

 to become fully developed, we can calculate, within a few days, the time 

 when the winged insects will be most numerously leaving any part of 



