Short Communications. 571 



to end, are completely defoliated. Their depredations cease 

 when their change into the chrysalis state takes place, leaving 

 the trees covered with the webs (or, rather, silky threads) by 

 which they transport themselves from place to place ; and 

 every leaf shrivelled, as if scorched by fire. Shortly after 

 the exit of the caterpillars, the trees and hedges regain their 

 verdure; but, if any of the fruit itself escape their ravages, it 

 is, in consequence of their attacks on the leaves, small and 

 worthless. 



The family of moths are particularly partial in their choice 

 of food, one species affecting one order of plants only. So 

 much is this the case, that entomologists have thought fit to 

 identify them by cognomens derived from the names of plants 

 on which they are found : as, (Sphin^r tiliae, the lime tree moth; 

 S. convolvuli, the bindweed moth ; and S. ligustri, the privet 

 moth. The instinctive predilections of these little creatures 

 have often suggested the idea that their favourite plants might 

 be defended from their visits by the qualities of other plants 

 to which they are averse. This, indeed, is an old idea : fifty 

 years ago, farmers were advised to protect their young tur- 

 nips by drawing over every part of the field a bush-harrow 

 made of the branches of common elder. For the same pur- 

 pose, I have myself, many years back, watered my April- 

 sown cauliflower seedlings with an infusion of the leaves of 

 artichokes, a liquor bitter enough, certainly; but neither 

 elder on the field, nor the decoction of artichoke leaves on 

 the garden, answered the purpose for which it was applied. 

 In these attempts, we proceeded on the supposition that the 

 palates of the insects were similar to our own ; and that what 

 was nauseous to us must also be so to them : here lay our error. 



Notwithstanding these failures, it is still highly probable 

 that the qualities of those plants so pertinaciously rejected by 

 the insects might be, if properly extracted, available, if not 

 to destroy, at least to disgust, them ; which would equally 

 effect our purpose, namely, the preservation of useful or 

 ornamental plants. 



I was more than ever struck with these ideas from an ob- 

 servation made by yourself, when, on a late occasion, I had 

 the pleasure of walking with you round your garden at Bays- 

 water. You were lamenting the ravages of the Tinea padella, 

 and pointedly alluded to the untouched and lively verdure of 

 the ivy, compared with apple trees close at hand, stretching 

 forth their " naked arms " to the sky. I believe I mentioned 

 at the time, that, were it practicable to transfer the qualities 

 of the ivy, in a fluid state, upon the foliage of the apple, the 

 latter would be thereby protected from the attack of the moths 



