62 OUR SHADE TREES AND THEIR INSECT DEFOLIATORS. 



of a fortnight later in the season, will prove au effectual protection to 

 trees of all kinds. This can be done at small expense, and will prove 

 the salvation of the trees. An apparatus can be readily constructed, 

 such as has been used on the grounds of the Department of Agriculture, 

 on a sufficiently large scale to economize time and labor. It should con- 

 sist of a water tank mounted on a cart and furnished with a strong 

 force pump operated by one man and furnished with two sets of rubber 

 tubing of a sufficient length (a hose reel can be constructed on tot) of 

 the cart), each hose supported by a bamboo extension pole with a cyclone 

 nozzle at tip. With such an apparatus as this three men could drive 

 along the streets and thoroughly spray two trees simultaneously ; while 

 if it were found advisable, four independent tubes and four men to 

 work them could be employed with a sufficiently powerful pump, and 

 thus expedite the work. The details of the more important devices 

 connected with this tank-cart are given in considering the Galeruca. 

 The bamboo "extension pole'' is used simply to stiffen the rubber hose 

 and to enable the operator to elevate the spraying nozzle into the center 

 of the tree and spray to a so much greater height. The same result 

 can be accomplished by means of a brass rod, in sections, and this has 

 the advantage of superior strength, and will consequently carry a 

 heavier nozzle or a bunch of nozzles at the end. 



The "Cyclone" or "Eddy-chamber" nozzle (see Fig. 6) is better suited 

 for work of this kind on small trees than any yet in use. It is small, 

 simple, cheap, will not clog, and gives an admirable spray. A combi- 

 nation nozzle may be made of several of these which will be readily 

 supported by the section rod and will throw a more profuse spray. 



The arsenical compound known as London purple is, as already 

 shown, perhaps preferable to white arsenic or Paris green in that it is 

 not so liable to burn the leaves while its color enables one to readily 

 distinguish poisoned from non-poisoned trees. Moreover it is very 

 cheap. From one-quarter to three-quarters of a pound of this substance 

 should be used to a barrel of water, and with this quantity of water it 

 is best to mix three quarts of cheap or damaged flour w T hich will serve 

 both to render the mixture adhesive to the leaves and also to lessen the 

 tendency of the poison to burn the leaves. Three-quarters of a pound 

 to the barrel may prove too strong a mixture for delicate and susceptible 

 young trees, and it will be best for general application to make the 

 amount from three-eighths to one-half pound to the barrel. Paris green 

 will require a somewhat heavier dose — say from one-half to 1 pound 

 per barrel of water. 



A number of other means have been tried and are more or less effect- 

 ual in destroying these defoliators. Such are the application of various 

 other insecticides, particularly an emulsion of milk and kerosene, the 

 burning of the webs (in case of the web-worm) by thrusting a lighted 

 torch, made of various patterns, into the webs: but after full trial, 

 nothing has been found more satisfactory than the arsenical mixtures 



