go BRITISH GALLS 



the Continent ; the habits of any one species of insect are 

 the same every where, . though it is possible, as the Rev. 

 E. N. Bloomfield has pointed out to me, that the insect may 

 cause a gall on an allied plant, and in some cases on various 

 plants, and the one it favours in Britain may be one on 

 which it is not found on the Continent. There are several 

 Continental records of homopterous galls on plants which 

 find a place only in the alien flora of this country. These 

 insects have been recorded as British, and it is possible they 

 may have been introduced on the plants in question; but 

 until we have certain evidence, of their causing galls on 

 them in Britain, it is advisable to omit them from the cata- 

 logue of British gall-causing insects. 



Experimental Grails 



Peyritsch, experimenting with Aphidae in 1888, produced 

 modifications of the floral organs, chiefly swollen axis and 

 chloranthy, in species of A rabis. The same observer recorded 

 that Trioza cerastii H. Low, a species not recorded as British, 

 caused a rounded gall consisting of numerous imbricated 

 leaves on the stem of Cerastium glomeratum. 



Economic Notes 



The order Homoptera includes some of the most trouble- 

 some of all pests. The rapidity of production, and the fact 

 that its members feed throughout life easily, explain why the 

 family Aphidae contains the worst offenders. Several are 

 well-known gall-causers, and the majority that have been 

 alluded to in this chapter often cause serious losses. Informa- 

 tion concerning these and many others may be obtained in 

 the leaflets issued by the Board of Agriculture, and in Miss 

 Ormerod's " Manual." It may be mentioned here that a 

 simple method of destroying Aphidae is to spray affected 

 plants with a wash made of 10 pounds (or less) of soft soap 

 dissolved in loo'gallons of soft water ; the soap kills them by 



