166 TRANSACTIONS OF THE ILLINOIS 



right time to every limb and twig, might be an entire success. No remedy applied to 

 the trunk of the tree ever was, or ever will be, destructive of the louse on the limbs, no 

 matter how it may be applied, either by applying on the surface of the bark, or by de- 

 positing in a hole in the body of the tree, except it kills the tree, and then, of course, 

 it will be eft'ectual in killing the louse also. It is just as reasonable to suppose that we 

 can kill lice on the body of an animal, or on man, by using Internal remedies, as to 

 suppose that we can kill the lice on a tree by medicating the tree . The greatest bark 

 louse exterminator ever discovered, is Auriis malus, an insect belonging to the niite 

 family . It feeds upon the eggs and young bark lice , as I have shown in the Transac. 

 tions of the American Entomological Society, Jan. , 1868, and in the Trans. Ills. State 

 Hort. Soc. for 1868, published in 1869, and as Mr. Walsh has also shown in his "First 

 Annual Report on the Noxious Insects of the State of Illinois," page 44, from his own 

 independent observations. We both discovered this very important parasite independent 

 of each other during the summer of 1867. No other insect, or device, can compare 

 with it for efficiency, and probably nothing except inclement weather will ever excel it. 

 The desire among us all is to disco\'er something that we can apply at will by, our own 

 art that will destroy the bark louse eflectually. But what shall we use or try that has 

 not been tried already. Among parisiticides, corrosive sublimate has no ec(ual ; it will 

 kill the bark louse. But the only question is, can it be applied so as not to kill the tree 

 also. According to Bouchardat, plants are poisoned by solutions containing a thou- 

 sandth part of this drug— Stillc. Therapeutics, Vol. 2, p. 659. In 1867 I commenced 

 experimenting with this, using it at the rate of one pound to the barrel of water; this 

 applied in the month of June killed all the bark lice, but appeared to injure the bark 

 of the tree. Since then I see that the cuticle was destroyed and peeled off. I also 

 made applications at the rates of one ounce, and four ounces to the barrel of water, 

 without any eifect on the ^^hark-Uce.'" 



Weak solutions of carbolic acid, sulphite of soda, and such like drugs, might reason- 

 ably be tried. Another great desideratum is a machine to apply any agent safely and 

 at the same time economically. I have often thought that a large machine that would 

 operate on the principle of the medical spray apparatus might be etfectual and useful 

 in applying lotions and washes of any kind to the small limbs and twigs of trees. 



I also ascertained that strong solutions of soap will kill the young bark-louse, when 

 it is running on the tree, but very soon after it attaches itself it is protected by an 

 impervious case from such mild applications. Such applications will be quite effectual 

 if applied just the right day, as in a year like 1867, when I saw most of the bark-lice 

 running on one day — June 9th; but as is usual, when they hatch on successive 

 days, during a week or ten days, it -ijecomes more difficult to kill them by local 

 applications, foi", as I have heretofore shown, the young bark louse attaches to the 

 tree and forms the first segment ot its scale before sundown of the day of its birth, 

 luiless prevented by accident; and it Avoidd be a great task to syringe the trees over 

 with soap suds every day for ten days at the hatching time of the young bark louse. 

 Mr. Walsh, in his Annual Report, p. 46, after a series of experiments, also concludes 

 that soap suds will kill the bark louse shortly after it is hatched, l)Ut it has no eflect 

 upon the perfect scale; that scrubbing the trees with a stiff brush will break up the 

 young scale, but that the old matured scale can only be removed by the edge of a 

 knife oi' other such tool ; both of which methods are not very practical on the small 

 twigs or branches. He also concludes that strong alkaline washes and tobacco water 



