830 



ON THE CULTURE 



house. For this reason no water should be given 

 over the leaves of the plants, in less time than six 

 weeks from their dressing, as I have already 

 observed, d 



d Soap-suds effectually destroy the different species of insects 

 that infest fruit-trees growing against walls. Of these insects 

 the Aphis is the most common, as well as the most destructive. 

 It generally attacks, with great violence, the peach, cherry, and 

 plumb. The Aphides are universally known by the appellation 

 of Lice. 



The Acarus, though not so fatal to plants growing in the 

 open air as when under glass, is also very prejudicial to the 

 above trees, when planted against walls. 



The Thrips are sometimes very numerous on peach and 

 nectarine trees ; but they are less hurtful than either of the 

 former species. Besides the above, there are two or three sorts 

 of the Cocci that are very common upon fruit-trees ; but, as 

 they adhere very closely to the branches, they are not so con- 

 spicuous, and consequently less known. However, trees that 

 are much infested with the Cocci are in the summer very dis- 

 tinguishable, as wasps constantly attend these insects, to feed 

 on the sweet matter that issues from them. When the muscle- 

 shaped Coccus has been very numerous, I have known hive-bees 

 frequent the trees in great abundance. 



In the spring, the Aphis, the Acarus, and Thrips, are few 

 in number, in comparison to what they are in the summer. 

 However, I have constantly observed the two former species 

 on the buds of the trees before they break into leaf, especially 

 on such trees as have been much infested with them the pre- 

 ceding summer. 



It is most probable that the insects that survive the winter, 

 in whatever state, are concealed during that period, either un- 

 der the branches of the trees, or in the shreds that fasten them 

 to the wall ; else in the nail-holes or crevices of the wall. In 

 all these situations the soap-suds have fully answered my most 



