NATURAL HISTORY. 



843 



" usually arc ; but in this respect 

 ** smoke has every advantage ; it 

 " penetrates and pervades their 

 *' inmost recesses. The smoke of 

 " common vegetables, however 

 " powerful, is found to be inade- 

 " quate to their destruction, and 

 '• hitherto no other than that of to- 

 " bacco is found to be etfectual. 

 " That, judiciously applied, com- 

 " pletely answers the purpose, with- 

 *' out injuring the plant. It mostly 

 *' happens, in well-managed houses, 

 " that a few plants only are infested 

 *' with aphides ; in such a case the 

 " smoking of the whole house is a 

 •' business of unnecessary expence 

 '* and trouble; and we would re- 

 '• commend it to persons who have 

 " large collections, to make use of 

 " a box, of a commodious form, 

 " that shall hold about a dozen 

 " plants of various sizes, to be used 

 " as a sort of hospital, in which 

 " the infested plants may be snioak- 

 " ed separately, and the insects 

 *' more effectually destroyed, be- 

 *' c^usc it may be rendered more 

 " perfectly smoke-tight." 



" To prevent the calamities which 

 *' would infallibly result from the 

 *' accumulated multiplication of the 

 " more prolihc aniaials, it has been 

 " ordaiii'jd by tiie Author of na- 

 *' ture, that such should be dimi- 

 *' nishcd by serving as food for 

 " others. On this principle we find 

 " that most animals in this predica- 

 *' ment have one or more u;itural 

 " enemies. The helpless aphis, the 

 " scourge of the vegetable king- 

 *' dom, has to contend with many. 

 *' The priiicip;il are, the cocinel/a^ 

 " the i linfitinon uplu'diim, and the 

 " I'ticsca (tphidrcura. Such as are 

 " unacquainted with the history of 

 " insects, wiH learn «ilh surprise, 

 " that the toccinella, a common in- 



" sect, well known even to children 

 " by the name of the lady-bird, is 

 " one of the greatest destroyers of 

 " the aphides, which indeed are its 

 " only food, its sole support, as 

 " well in its perfect as in its larva 

 " or grub state. During the seve- 

 " rity of winter, this insect secures 

 " itself under the bark of trees or 

 *' elsewhere. When the warmth of 

 " spring has expanded the foliage 

 " of plants, the female deposits its 

 " eggs on them in great numbers, 

 " from whence, in a short time, 

 " proceeds the larva, a small grub,- 

 " of a dark lead colourspotted with 

 " orange: these may be observed 

 " in the summer season, running 

 " pretty briskly over all kinds of 

 " plants; and if narrowly watched, 

 " they will be found to devour the 

 " aphides wherever they find them. 

 " The same may be observed of the 

 " lady-bird, in its perfect state. As 

 " these insects, in both their states, 

 " are very numerous, they contri- 

 " bute powerfully to diminish the 

 " number of aphides. Another most 

 " formidable enemy to the aphis is, 

 " a very minute black and slender 

 " ichneumon tiy, which eats its way 

 " out of the aphis, leaving the dry 

 " inflated skin of the insect, ad- 

 " hering to the leaf like a small 

 " pearl. Such may always be found 

 " where aphides are in plenty. 

 " We have observed dilferent spe- 

 " cies of aphides to be infested 

 " with different irhneumons. In 

 " general, the torpid aphis submits 

 "quietly to this fatal operation; 

 " but we have observed some of 

 " them, especially one that feeds on 

 " the sycamore, which is much more 

 " agile than many of this race, en- 

 " deavouring to avoid the ichneu- 

 " mon wi(h great address. There 

 ♦' is perhaps no genus of insects 



'< nhiili 



