Xo. 4.] SHADE-TREE INSECT PROBLEM. 103 



comes to a standstill until repairs, often expensive, can be 

 made. With the small outfits the temporary loss of even 

 t\vo or three will not prevent the continuance of effective 

 work by the remainder, and, as the parts are interchange- 

 able, frequently two broken pumps can be combined to put 

 one of them into working condition. 



Another objection to the use of power outfits is the in- 

 creased temptation to throw the solution onto the foliage in 

 a stream, instead of in a spray. The pump is backed by 

 adequate power, and nothing is easier for a lazy workman 

 than to open the nozzle and drench the tree, instead of 

 spraying it. Sprinkling is not spraying ; drenching is not 

 spraying. The only effective way to spray a tree and have 

 the poison remain on it is to apply the solution as a fine mist. 

 Take a lesson from nature ; the dew or fog coats the foliage 

 with minute isolated particles of water, which adhere ; the 

 drops of rain roll off. So it is with spraying. The poison 

 in the form of a mist-spray can be drifted into the tree, com- 

 mencing at the top, and the whole tree can be treated with- 

 out the loss of a single gallon of the solution. This is the 

 only right way to spray. The poison dries on the leaves, 

 and is in the right place when the insects arrive. I venture 

 to say that at least one-half of the poor results from spraying 

 are due to a lack of knowledge of how to apply the materials 

 to the foliage. 



The cost of spraying operations on the scale necessary in 

 park or town work is difficult to compute, yet on no other 

 point is information so much needed by those in charge of 

 trees. The experience of others is the best guide, but even 

 this is difficult to obtain, as most workers very properly de- 

 vote their energies to spraying the trees, and consequently 

 ignore the details of daily or weekly records of work per- 

 formed. The writer, by dint of correspondence and personal 

 solicitation, has obtained the statements given below from 

 reliable sources, and would at this time make thankful ac- 

 knowledgment for the same. 



Mr. J. A. Pettigrew, superintendent of parks at Boston, 

 Mass., while holding a similar position at Brooklyn, N. Y., 

 sprayed 8,712 elms with London purple, at a total cost of 



