87 



fornia where the orange scale has l)een very troublesome, the im- 

 ported Australian lady-bird has been found very useful so that the 

 State Board of Horticulture raised the beetle for distribution 

 among orange growers, that by its aid the scale might be checked. 

 How valuable an aid this is, I do not know, as reports have not 

 yet come in very extensively. 



The second family of plant lice is called in the books the A/ey- 

 rodidce. Less appears to be known concerning this family than 

 of the others. They arc winged in both sexes. The color is 

 usually light, white or whitish, or yellow, and the distinguishing 

 character is found in the light powder which covers the bodies of 

 the adult insect. In the immature state they are covered with a 

 scale. I do do not know that any species of this family is found 

 on the elm. 



The third family are the Aphldidcc. These are the well-known 

 plant lice which are more familiar to most than others of the group. 

 The common green fly of the gardeners may be taken as a type of 

 this family. A considerable number of injurious insects belong to 

 this group. In his excellent Synopsis of the -(4phidida3 of Min- 

 nesota, Mr. Oestlund has enumerated five species of Aphides 

 which are found upon the American elm, and one which is con- 

 fined to the slippery elm. It is more than likely, however, that 

 when the group has been more thoroughly studied, this number 

 will be increased. The family embraces a very large number of 

 species infesting a great variety of plants. All are very small ; 

 most are soft-bodied, delicate insects, with four very thin trans- 

 parent wings, or in many stages without wings. Like the Coccidce 

 these insects secrete honey dew at certain times in considerable 

 (juantities, and all are familiar with the fondness which ants mani- 

 fest for this sweet substance. Other insects also feed upon it, but 

 ants more than others. Tiie changes which the Aphides undergo 

 as they pass from brood to brood, will be better understood by tiie 

 illustrations which follow, than by any general description. As 

 will be seen, their modes of multiplicaton are peculiar. Many of 

 them so affect the parts of plants which they infest that galls, 

 swellings, crinklings, and other deformities arc produced. The 

 first sjDccies of this group to be considered is 



THK EI.M I, EM" CRl'MPI.KU. 



This insect, Scliizotieitra anicricanay Riley, isofmucli interest, 

 i8 



