844 



ANNUAL REGISTER, 1805. 



*' which in their larva or maggot 

 *' state, feed on such a variety of 

 *' food as the tmifca, or fly. There 

 *' is scarcely a part of nature, 

 *' either animate or inanimate, in 

 " which they are not to be met 

 *' with. One division of them, 

 *' called by Linnaeus miisde aphidi- 

 *' vorce, feeds entirely on apiudes. 

 " Of the different species of aphidi- 

 " vorous flies, which are numerous, 

 *' having mostly bodies variegated 

 *' with transverse stripes, their fe- 

 *' males may be seen hovering over 

 *' plants infestedwith aphides,among 

 *' which they deposit their eggs on 

 *' the surface of the leaf. The lar- 

 *' va or maggot produced from such 

 *' eggs, feeds, as soon as hatched, 

 *' on the younger kinds of aphis, 

 " and as it increases in size, attacks 

 ".and devours those which are lar- 

 " gcr. These larva are usually of 

 *' a pale colour, adhere closely to 

 *' the leaf, along which they slowly 

 *' glide, and are formed very taper- 

 " ing towards the head. When fully 

 *' grown, they change to a pupa or 

 *' chrysalis, attached to the leaf, 

 *' from whence issues the fly. The 

 *' larvae of these flies, contribute 

 " their full share to diminish the 

 *' despoilcrs of Flora. To these 

 " three kinds of insects, which are 

 " the chief agents in the hands of 

 " nature for keeping the aphides 

 " within their propci" limits, we may 

 *' add a few others, which act a 

 *' subordinate part in this ncces- 

 *' sary business of destruction. The 

 *' larva of the hemerohius feeds on 

 *' theui in the same manner as that 

 *' of the mitsca aphidivora, and de- 

 *' posits i*s eggs also on the leaves 

 *' of such plants as are beset with 

 *' aphides. The eggs of this heme- 

 *' robius stand on long filaments, 

 *' which are attached by a base to 



3 



" the leaf, and have more the ap.* 

 " pea ranee of filaments of flowers 

 " with their anthers, than the eggs 

 " of an animal. The number of 

 " these insects being comparatively 

 " small, they nuiy be considered 

 " rather as the casual invaders of 

 " their existence, than the main host 

 '• of their destroyers. The earwig, 

 " which is itself no contemptible 

 " enemy to plants, makes some 

 " atonement for its depredations, by 

 " destroying the aphides, especially 

 " such as reside in the curled-up 

 " leaves of fruit trees, and the 

 " purses formed by certain aphides 

 " on the poplars and other trees. 

 " Lastly, we may add as the ene- 

 " mics of these creatures, some of 

 " the smaller soft-billed birds, which 

 " generally feed on insects, and 

 " which may be frequently seen 

 " busily employed in picking them 

 " from the plants." 



" When plants assnme a sickly 

 " appearance, or arc disguised by 

 " disease, from whatever cause 

 " the disease may arise, they are 

 " said to be blighted. Blights ori- 

 " ginate from a variety of causes, 

 " the chief of which arc unfortunate 

 " weather, and insects. Two opi- 

 '• nions prevail very generally in 

 " regard to blights ; the one, that 

 " the insects which cause them, arc 

 " brought from a distance by easter- 

 " ly winds ; the other, that they 

 " attach themselves to none but 

 " plants already sickly. Neither 

 " of these opinions, as far as I have 

 " observed, is founded in fact. I 

 " am induced, from the numerous 

 " observations I have made on in- 

 " sects for a series of years, (in 

 " pursuing the cultivation of plants) 

 " to consider the aphis as by far the 

 " most general cause of the diseases 

 " distinguished by the name of 



" blights. 



