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 whiteness, may be collected from the cocoons even of the Ichneumons that destroy the larvae 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, particularly 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 recollect that the very small quantity of purple dye afforded by the Purpura of the ancients did not prevent them from collecting it.

I now conclude this long series of letters on the inju. ries caused by insects to man, and the benefits which he derives from them; and I think you will readily admit

Voyage dans l'Amer. 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. Dict. d'Hist. Nat. ii. 280.

C

American Phil. Trans. v. 325.

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

that I have sufficiently made good my position, that the study of agents which perform such important functions in the economy of nature must be worthy of attention. Our subsequent correspondence will be devoted to the most interesting traits in their history, as their affection to their young, their food and modes of procuring it, habitations, societies, &c.

I am, &c.

LETTER XI.

ON THE AFFECTION OF INSECTS FOR

THEIR YOUNG.

AMONGST the larger animals, every observer of nature has witnessed, with admiration, that love of their offspring which the beneficent Creator, with equal regard to the happiness of the parent and the progeny, has interwoven in the constitution of his creatures. Who that has any sensibility, has not felt his heart dilate with gratitude to the giver of all good, in observing amongst the domestic animals which surround him, the effects of this divine storgé, so fruitful of the most delightful sensations? Who that is not å stock or a stone has read unmoved the anecdote recorded in books of Natural History, of the poor bitch, which in the agonies of a cruel dissection licked with parental fondness her new-born offspring; or the affecting account of the she-bear related in Phipps's Voyage to the North Pole, which, herself severely wounded by the same shot that killed her cubs, spent her last moments in tearing and laying before them the food she had collected, and died licking their wounds?

These feelings you must have experienced, but it has scarcely occurred to you that you would have any room

for exercising them in your new pursuit. You have not, I dare say, suspected that any similar example could have been adduced amongst insects, to which at the first glance there seems even something absurd in attributing any thing like parental affection. An animal not so big perhaps as a grain of wheat, feel love for its offspringhow preposterous! we are ready to exclaim. Yet the exclamation would be very much misplaced. Nothing is more certain than that insects are capable of feeling quite as much attachment to their offspring as the largest quadrupeds. They undergo as severe privations in nourishing them; expose themselves to as great risk in defending them; and in the very article of death exhibit as much anxiety for their preservation. Not that this can be said of all insects. A very large proportion of them are doomed to die before their young come into existence. But in these the passion is not extinguished. It is merely modified, and its direction changed. And when you witness the solicitude with which they provide for the security and sustenance of their future young, you can scarcely deny to them love for a progeny they are never destined to behold. Like affectionate parents in similar circumstances, their last efforts are employed in providing for the children that are to succeed them.

I. Observe the motions of that common white butterfly which you see flying from herb to herb. You perceive that it is not food she is in pursuit of; for flowers have no attraction for her. Her object is the discovery of a plant that will supply the sustenance appropriated by

Providence to her young, upon which to deposit her eggs. Her own food has been honey drawn from the nectary of a flower. This, therefore, or its neighbourhood, we might expect would be the situation she would select for them. But no: as if aware that this food would be to them poison, she is in search of some plant of the cabbage tribe. But how is she to distinguish it from the surrounding vegetables? She is taught of God! Led by an instinct far more unerring than the practised eye of the botanist, she recognises the desired plant the moment she approaches it, and upon this she places her precious burthen; yet not without the further precaution of ascertaining that it is not preoccupied by the eggs of some other butterfly! Having fulfilled this duty, from which no obstacle short of absolute impossibility, no danger however threatening, can divert her, the affectionate mother dies.

This may serve as one instance of the solicitude of insects for their future progeny. But almost every species will supply examples similar in principle, and in their particular circumstances even more extraordinary. In every case (except in some remarkable instances of mistakes of instinct, as they may be termed, which will be subsequently adverted to) the parent unerringly distinguishes the food suitable for her offspring, however dissimilar to her own; or at least invariably places her eggs, often defended from external injury by a variety of admirable contrivances, in the exact spot where, when hatched, the larvæ can have access to it.—The dragonfly is an inhabitant of the air, and could not exist in water: yet in this element, which is alone adapted for her