DIRECT BENEFITS DERIVED FROM INSECTS. 283 



which the mhabitants of Chilpancingo, Tixtala, &c., in 

 America, manufacture into stockings and handkerchiefs.' 

 Great numbers of similar nests of a dense tissue, resembling 

 Chinese paper, of a brilliant whiteness, and formed of distinct 

 and separable layers, the interior being the thinnest and ex- 

 traordinarily transparent, were observed by Humboldt in the 

 provinces of Mechoacan and the mountains of Santarosa, at a 

 height of 10,500 feet above the level of the sea, upon the 

 Arbutus Madrono, and other trees. The silk of these nests, 

 which are the work of the social caterpillars of a Bombyx 

 (^B. Madrono), was an object of commerce even in the time of 

 Montezuma; and the ancient Mexicans pasted together the 

 interior layers, which may be written upon without prepar- 

 ation, to form a white glossy pasteboard. Handkerchiefs 

 are still manufactured of it in the Intendency of Oaxaca.^ 

 De Azara states that in Paraguay, a spider, which is found 

 to near the thirtieth degree of latitude, forms a spherical 

 cocoon (for its eggs) an inch in diameter, of a yellow silk, 

 which the inhabitants spin on account of the permanency of 

 the colour.^ And according to M. B. de Lozieres, large 

 quantities of a very beautiful silk, of dazzling Avhiteness, may 

 be collected from the cocoons even of the Iclmeumons that 

 destroy the larvse of some moth in the West Indies, which 

 feed upon the indigo and cassada.* 



It is probable, too, that other articles besides silk might be 

 obtained from the larvae which usually produce it, particu- 

 larly cements and varnishes of different kinds, some hard, 

 others elastic, from their gum and silk reservoirs, from which 

 it is said the Chinese procure a fine varnish, and fabricate 

 what is called by anglers Indian grass, ^ The diminutive size 

 of the animal will be thought no objection, when we re- 

 collect that the very small quantity of purple dye afforded 



1 Annals of Botany, ii. 104. 



2 Political Essay on N. Spain, iii. 59. 



3 Voyage dans VAmer. Merid. i. 212. It may here be observed as a benefit 

 derived by the higher walks of philosophy from insects, that astronomers employ 

 the strongest thread of spiders, the one namely that supports the web, for the 

 divisions of the micrometer. By its ductility this thread acquires about a fifth 

 of its ordinary length. Nouv. Diet. d'Hist. Nat. ii. 280. 



American Phil. Trans, v. 325. 

 ^ Anderson's Recreations in Agriculture, &c. iv. 399. 



