304 DESTRUCTIVE INSECTS, 



it is under 50 of Fahrenheit. The first broods in 

 the spring- issue from eggs deposited on their favourite 

 trees in the previous autumn ; and from these all 

 the sequential broods of summer proceed. Rose trees 

 require to be particularly well guarded against these 

 autumnal depositions. Other insects besides the 

 aphides choose this plant for their young, the larva 

 of which roll themselves in the leaves, or eat a way 

 into the flower, but which they devour before it is 

 expanded ; in like manner many other fruit and 

 flowering trees are damaged. If then any easily dis- 

 tributable matter, either dry to be applied with a puff, 

 or a liquid discharged by a syringe, were given from 

 time to time in the autumn, there is no doubt of its 

 operation as a defence. In fact it is only making the 

 plants disagreeable arid uninviting to the parent 

 insect, that will save it from the ravages of the off- 

 spring. 



Salts, particularly alkaline salts, lime, sulphur, or 

 other mineral substances, and all pungent decoctions, 

 are to some one insect or other either offensive or 

 fatal: and many vegetable qualities doubtless there 

 are, which, however innocuous and even nutritious 

 to the human frame, may be highly disgusting to 

 many insects which annoy us. Such are desiderata 

 yet to be discovered by attention and experience . 

 and, in the search, it should be remembered, that the 

 human palate and that of insects are dissimilar ; the 

 aphides riot OH the hop, the elder, and other bitter 

 plants, but which, perhaps, would quickly perish on 



