420 



MINNESOTA STATE HORTICULTURAL SOCIETY. 



during- fall, winter and early spring- will kill the great majority; and 

 this method of fighting such lice is b}' all odds the best in Minnesota, 

 and by doing so, we can eventually kill them root and branch. The 

 peculiar honey-dew, largely produced by these insects earl}^ in sum- 

 mer, frequently coats all the leaves, and as it is a fine mediuiu for 

 the growth of some fungi, the leaves soon appear as if coated with 

 soot. 



Fig. fi. a. PLUM GALL MiTE; h, section through gall; c, gall-maker: 

 d. winter-eggs of PLUM APHLS; a and d, nat. size; b and c, greatly enlarged. 



The Plum Gall Mite, (Fig. 6, a, b and c) is produced by a ver}^ 

 minute mite (Fig. 6, c), a member of the order of spiders. It is not a 

 true insect. As you all know, spiders differ from insects by having 

 eight, not six legs, by having the body into two parts, not into three, 

 as in the case with insects. Mites again are separated from spiders 

 in not having a deep constriction between cephalothorax and abdo- 

 men, and by having but three pair of legs when young. The mites 

 which produce galls or other deformations are mostly members of 

 of the genus Phytoptus, distingviished by the possession of onl}^ 

 two pairs of legs. They are lowly organized inites, possess a verj^ 

 elongated and transversel}^ striated body, and are all injurious to 

 plants. Being extremely small, they have not been studied in the 

 United States to any extent, in fact, most of them have not even re- 

 ceived a name. Until 18.")1, they were considered as the larvae of 

 other mites, but now we know that they are adults. The two pairs 

 of five-jointed, strongly compressed legs are cld^e to the rostrum 

 upon the extreme anterior portion of the body. The number of 

 transverse striie varies in different species. Some have MO, others 

 55, and still others as many as 80 and more. Nothwithstanding their 

 small size, they move rapidly by means of their legs, dragging the 

 long abdomen after them. A terminal disk assists them to cling 

 to the surface upon which they move, and is also utililized to take 

 hold of whatever it touches. As far as known, the mites hibernate 

 in the buds and begin their attacks early in spring. They attack 

 the unfolding leaves, and bj^ inserting their rostrum in the luider 



