PACivARD.] THE POPULATION OF AX APPLE TREE. 189 



rous with the whigs. On the top of the head is a conspicu- 

 ous bushy tuft of bright reddisli orange hairs. The legs are 

 of a leaden hue, the hairs yellowish, the hind shanks long 

 and hair}', with four long, slender spurs ; the antennae are 

 dark on the terminal three-fourths, pale orange at base. 

 The under side of the wings are leaden gfa^-. The length 

 of the body is '07, and of the body including the folded 

 wings, one-tenth of an inch. 



Tlie Sac Bearer. — Another winged gem, with a still more 

 curious childhood than the Micropterj'x, is a sac bearer, as 

 the Germans call it. Like a boy in a meal sack, with his 

 arms sprawling about and pulling himself along, the little 

 caterpillar pokes its head out of its case, extends its six fore 

 legs, like so many hands, and pulls itself over the leaf, its 

 little world. The worm is flattened, green, and no thicker 

 than a small knitting needle. The case or sac is oval, open 

 at each end, much flattened and roomy enough for its inhab- 

 itant to turn around in. How the case is constructed we 

 have been unable to observe. While some sac bearers cut 

 an oblong slit in the leaf, fold it over, and then cutting a 

 corresponding slit remove the folded portion, fasten together 

 with silk the open side, wriggle into this straight jacket, and 

 walk off as if they had been born with their houses on their 

 backs ; others probably construct their cases out of fine bits 

 of leaf stuck together Avith tlie silken glue secreted frona the 

 glands emptying into their mouths. The material of such 

 cases resembles a thick, felt-like cloth, and that of our sac 

 bearer is of this nature. By the end of August the caterpil- 

 lar becomes mature and ready to transform into a chr^'salis. 

 It does not desert its old coat, but hangs it by a few threads 

 to the bark of the tree and contracts its body, lies quiet 

 through the winter, until early in summer the cluysalis 

 breaks through a rent in its skin and soon after the moth 

 appears. It is now one of the most beautiful objects in 

 nature. It is very small, the head finely dusted, its softly 



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