65 



the head of it being close to their bellies: they carry 

 these to little holes in the ground. In the first they 

 Jay their eggs ; then they bring others to be food for 

 their young when hatched. One fly is not enough ; 

 therefore their parents carry them more every day, 

 crawling backward into the hole, and dragging in the 

 flies after them. When the worms change into aure- 

 lia, their cases are made of the exuviae of the flies they 

 have been feeding on. 



The eggs of insects arc usually the occasion of what 

 are termed blights. These seldom happen but on the 

 blowing of sharp easterly winds. Many insects at- 

 tend those winds, and lay their eggs 0:1 proper plants. 

 Indeed the large worms or caterpillars which attend 

 some blights, seem to be only hatched by those winds, 

 But they probably bring those swarms of insects which 

 occasion the curling of the leaves of trees. 



Every insect feeds on one plant and ao other. On 

 this only it lays its eggs. Hence it is ; that one kind 

 of tree only is blighted, and the rest escape. All trees 

 then cannot be blighted at once, unless one wind could 

 bring the eggs of all insects, with as many different 

 degrees of heat and cold as are required to hatch and 

 preserve each species. 



And what though we do not always perceive ani- 

 mals in blights, by microscopes we disco veranimalcu- 

 la a million times less than those that are perceivable 

 by the naked eye. The gentlest air may waft these 

 from place to place, so that it is no wonder if they are 

 brought to us from Great Tartary ; even the cold air 

 of which may give them life, and from whence there is 

 not so much sea as to suffocate them in its passage, by 

 the warmth and saltness of its vapours. 



Trees are preserved from blights by sprinkling them 

 with tobacco. dust or pepper-dust, which are death to 

 all insects. 



But one kind of blight is caused, merely by long 

 continued dry easterly winds. These stop the perspi- 

 ration in the tender blossoms, so that iu a short time 

 they wither and decay ; soon af-fcr, the tender leaves 



