WOOLLY APHIS. 185 



oil, mixed and put on ^Yarm, and, in fact, anything 

 that will thus choke the bark, is an unsafe appli- 

 cation. 



For attack below ground, the best treatment seems 

 to be, clearing away infested roots and soil round 

 them, and drenching the spot well with soft-soap 

 washings or drainings from stables. 



We have only six kinds of Schizoneura, and these 

 may be known by the one-forked wing-nerve, and by 

 having either no honey-tubes (cornicles), or exceed- 

 ingly small ones. (See Fig. 141, p. 183). 



The trihe of Pcmphigince is generally known from 

 the others by having no forks to the third wing-nerve ; 

 also by having the cornicles absent, or rudimentary.* 



This division hardly concerns us agriculturally. 

 There are only about seven British kinds, and, like 

 the above, they live in very various places ; some are 

 Gall-makers, and one does a great deal of harm at 

 Lettuce roots. When this is at work, it is desirable 

 to water well with anything that will keep the soil 

 thoroughly moist, and be favourable at the same time 

 to growth ; bearing in mind that below ground, as 

 well as above, the great point in killing Aphides is to 

 apply something that will choke up their breathing- 

 pores, as mere water, or merely fluid applications, 

 flow off them, unless special measures for flooding 

 are adopted. t Also, when ground is known to be 

 infested, it is very desirable to put on a killing 

 dressing : a handful of fresh gas-lime, put into each 



* The Pemphigina have usually no fork to the titird wing-nerve ; 

 but in the ease of the veiy small TJiclaxes dnjophila, sometimes found 

 on Oak, this third oblique wing-nerve haa one fork. The history of 

 Aphis life is so involved that it is very dillicult to convey any plain 

 and clear general view ; but in the above short sketch I have 

 endeavoured to give a correct abstract of tlie present state of in- 

 formation on the subject, following the classification given in Mr. 

 G. B. Buckton's admirable work, ' Monograph of British Aphides.' 



t It has been noticed by Mr. Buckton (' British Aphides,' vol. i., 

 p. 35) that "complete submergence in water speedily kills most 

 Aphides," — an important observation, well worth consideration in 

 the case of root-feeding Aphides. 



