1880.] 



AXV HORTICULTURIST. 



19 



>3picuous on the upper side. At a later time these ] 

 «pots turn brown by the death of the parts, after 

 which they are more easily discovered beneath. 

 With a good magnitier a minute hole can be dis- 

 tinguished near the centre of each spot through 

 'the lower side epidermis, and the spots are 

 somewhat thickened. This is about all that can 

 be ascertained with a hand magnifier, for if we 

 •dissect the spots notlring can ordinarily be found 

 but the spongy cell-tissues brown with disease or 

 •death. But if one of these spots is carefully 

 •opened and magnified fifty to one hundred times 

 numerous peach-colored slowl3'-moving things 

 are discovered. These are the depredators cauglit, 

 if not in the act, with the evidence of their mis- 

 •doings in the same field of view. The size is 

 much less than that of any true insect known ; 

 •the length from extremity to extremity being 

 but .0055 of an inch and the width not more than 

 .0017. It would take nearly two hundred of 

 them placed end to end to measure an inch, and 

 -six hundred could march elbow to elbow within 

 that space. We cannot wonder, therefore, that 

 more has not been known about them or that 

 they were so long entirely unknown. They make 

 Tip, however, what they lack in square measure 

 l»y the multiplication table. Dozens, perhaps 

 «cores, occur in a single spot, and dozens of spots 

 may beifound on a single leaf. The two pairs of 

 legs are directed forward and the little thing 

 clumsily drags its body along not unlike the 

 larvae of the May beetles, usually known as 

 white grub-worms. Its progress is excessively 

 •slow. The perilous trip down the foot-stalk of 

 the leaf to the buds in autumn must be an 

 immense undertaking. Some of them do not 

 make it, for, whether from simple procrastina- 

 tion or a dread of attempting the great journey 

 to an unknown country, numbers remain and 

 ■fall with the leaf to the ground. Possibly this is 

 the way that slow dissemination takes place 

 from tree to tree in an orchard, yet it hardly 

 •seems possible that, though carried by the winds 

 to the very foot of a tree, they could climb the 

 trunk to the limbs. The chance would be better 

 in the nursery, where the leaves are very near 

 the ground. 



The fact referred to above as new, not having 

 heretofore been publicly announced, is that 

 these minute creatures do creep from their 

 galls in the leaves in autumn and pass the win- 

 ter within the leaf-scales of the buds. Hundreds 

 •of them may be found there now of the size and 

 form previously mentioned, and by keeping 



them warm for some time they may be seen 

 crawling as lively as nature ever permits them 

 to move. Neither eggs, except perhaps within 

 the body of the females, nor larvoe have been 

 observed, but they almost surely exist within 

 the leaf-galls. Probably my own investigations 

 have been made too late in the season. 



My story is longer than it should be, but there 

 must be a suggestion added as to the treatment 

 or remedy. Is the disease preventable or cura- 

 ble? Human beings sometimes, more is the 

 pity, have a skin disease popularly known as the 

 itch. Is it preventable or curable? It, too, is 

 caused by a mite, not distinctly related to the 

 little thing of which we speak. No one believes 

 this human parasite originates spontaneously 

 under the skin of the hand ; so we may rest as- 

 sured that when pear trees are thus affected — 

 catch the itch — they themselves are not the in- 

 cubators of the mite-species which causes it. The 

 mite comes from abroad, is disseminated in scions 

 and very gradually spreads from tree to tree 

 located near each other. Its marks in spring 

 and summer are conspicuous enough. Is not the 

 road to extermination evident enough? Let war 

 be made by cutting back the one-year-old wood 

 of all eff'ected trees in winter and burning the re- 

 moved portions. Then in spring-time remove 

 every young shoot which shows the need of it, 

 and likewise destroy it. Let this be kept up 

 during the summer and we may be sure that the 

 next season will show us healthy trees in this 

 respect. Most care should be taken with nurse- 

 ries, and especially in the selection of buds and 

 scions for propagation. Seedling stocks may be 

 contaminated ; in one ease they were known to 

 be. If such have the buds entirely cut away and 

 burned, and for further safety the roots dipped 

 into strong potash solution, no mites can escape. 

 The pruning advised may sometimes be severe, 

 but no large limbs need be removed, only last 

 year's growth, bearing the buds, and we may 

 proceed with the understanding that it is to be 

 done once, and once only if the work is thorough 

 and general throughout the orchard or nursery, 

 provided that some one else's orchard or nursery 

 does not closely adjoin that operated upon and 

 new importation of the mite is not made. 



Believing that no good reason exists for the 

 generic separation of this little creature from its 

 kindred previousl}- described, Andrew Murray 

 classes it among the species of the genus Phy- 

 toptus. This is almost certainly correct, and we 

 write to close with — Phytoptus pyri. 



