344 CONNECTICUT EXPERIMENT STATION REPORT, IQOO. 



All citizens should cooperate in giving timely notice of sus- 

 pected leaks, which, if not stopped, may soon kill valuable trees. 

 In some cities, when a tree has been killed by gas leaks, the 

 Company is required to pay the expense of removing it and 

 planting a new one under the direction of the City authorities. 

 Such a regulation seems eminently just, and its adoption in New 

 Haven is well worth considering. 



6. Insect Pests. Means of destroying Leaf-eating Insects. 

 Trees can be protected against all leaf-eating insects if the foli- 

 age is kept well covered with poison during the early part of 

 the summer. A thorough spraying should be given the trees 

 as soon as the leaves have unfolded, for if the elm leaf-beetles 

 can be poisoned before laying eggs the battle is won. Another 

 application should be made about two weeks later or as soon as 

 the young larvae begin to hatch out from the eggs. The second 

 spray should be directed against the under surface of the 

 leaves. In a dry season like the past, probably no other spray- 

 ing would be necessary, but if rains were frequent four appli- 

 cations might be required to keep the foliage well poisoned up 

 to the first of July. 



Arsenate of lead is perhaps the best poison to use for this 

 purpose. It has been employed during the last five or six years, 

 has given entire satisfaction and is considered superior to Paris 

 green by several competent and experienced men in charge of 

 street trees. 



It may be prepared as follows: 



Arsenate of Soda 4 oz. 



Acetate of Lead u oz. 



Water 100 gallons. 



The arsenate of soda and the acetate of lead should each be 

 dissolved in four quarts of water and then poured into the 

 spraying tank containing the required amount of water. This 

 mixture will not injure the foliage even if a much larger pro- 

 portion of poison is used. It should be stirred constantly to 

 insure uniformity in the mixture applied, though most spray- 

 ing outfits are provided with an agitator for this purpose. 



If trees cannot be sprayed, however, some good may be 

 accomplished by destroying the pupae of the Elm Leaf-Beetle 

 as they congregate at the base of trees. They may be gathered 

 and burned, or drenched with a mixture of I Ib. of whale-oil 



