STATE HORTICULTURAL SOCIETY. 153 



that is altogether exempt. Dig down to the roots of your apple trees or 

 grape vines, and you find them hid away, pumping with never-tiring 

 energy the fresh sap which the little fibrillae have just drawn from the soil ; 

 scrape the rubbish from the collar or base of the trunk, and there you see 

 their downy coats ; ascend the trunk, and at each abraded spot you will 

 find a colony located ; along the twigs you find other species busily 

 engaged ; nor are the leaves any more exempt. Pass from tree to tree in 

 the forest or grove, or from bush to bush in the nursery or garden, from 

 vegetable to vegetable in the kitchen garden, and from cereal to cereal 

 in the fields; enter the green-house or conservatory, or even the tiny 

 window garden, and still you find them at every turn, varying slightly 

 their plans of operation, but all busy at work pumping away the life of 

 the plant on which they are situated. 



For want of the works, I am unable at present to give a tabular 

 arrangement of the groups and genera according to the most recent 

 authorities. The following division into sub-families, which is substan- 

 tially that of Serville and Amyot, may be of use in determining species. 

 I regret that I am unable at this time to give Passerine's arrangement of 

 this family, in which there are more divisions than given here. This is 

 evidently defective, and is only given now as some aid in conveying an 

 idea of the different forms found in the family : 



1. Sub-family APHIDIN.«. 



Abdomen furnished near the extremity with two honey tubes, from which a 

 sweet fl#id escapes. 



2. Sub-family Myzoxylin^. 



Abdomen without tubes or tubercles ; species often covered with a cottony sub- 

 stance. 



Each of these sub-families contains several genera, the subdivision 

 being carried to a greater extent, probably, by Koch, than any other 

 author. 



Sub-family Aphidin/E. 



This sub-family includes such species as the Apple Plant-louse iAphis 

 mail), the Cabbage Plant-louse {Aphis brassiccB), the Wheat or Oat Plant- 

 louse {Aphis avencE), etc. The number of species is very large. Walker's 

 Catalogue enumerating three hundred and twenty-six besides those added 

 in the supplement. On this account entomologists have endeavored to 

 split up the old genus Aphis, which until recently corresponded exactly 

 with this sub-family ; they have therefore seized upon any permanent 

 character, no matter how minute, if confined to what appear to be, by 

 habit and otherwise, distinct groups. 



Genus Aphis. 



This contains those species which have the head small ; the eyes 

 globular and somewhat prominent ; the ocelli, or little eyes, usually want- 

 ing. Antennge is long or longer than the body, slender and tapering, 

 somewhat bristle-like, composed of seven joints, the first two of which 



