141 



to have greatly reduced the number of canker-worms on the trees, 

 knockitio- otT all but very small ones, and so checking- the injury 

 for the time beinii-. Tlio leaves of the infested trees were, how- 

 ever, already badly ridiUcd, and serious damage was certain to 

 occur. Ma}' S and *• the larger worms, half to three quarters of an 

 inch in length, which hail been knocked olT the trees, were found 

 on the trunks and larg^er limbs, evidently making- their way back 

 to the foliage. Only very small canker-worms could at this time 

 be found on the leaves, so small, indeed, as to show that eg-gs must 

 still be hatching-. 



Spraying began May *), workmen being- sent up into the trees 

 by means of forty- foot extension ladders furnished by the lire de- 

 partment, and then climbing far enoug-h to reach the outer 

 branches with their spray. The work was laborious, difficult, and 

 somewhat dangerous, but it was nevertheless continued with very 

 g-ood success until May 23, after which date the caterpillars had 

 nearly all g-ot their g-rowth and disappeared, and the operation 

 was suspended for the season. 



The insecticide used was that known as arsenite of lime, a solu- 

 tion of common arsenic in lime-water. Twenty pounds of arsenic 

 j^nd 10 pounds of lime were boiled in about 20 g-allons of water until 

 dissolved, — commonly for an hour or more,- and this stock solution 

 was diluted to contain a pound of arsenic to 300 g-allons. The 

 large sixty-foot elms required about 10 pounds of arsenic each. 

 Twelve-foot bamboo rods were used in distributing- the spray, with 

 a Vermorel or I>ordeaux nozzle at the end. The effect of the spray 

 was very quickly seen in the dead and dying- worms which fell 

 from the trees, littering- the sidewalks and g-rounds, where they 

 were greedily devoured by sparrows and appropriated also by ants 

 and other insects. 



One hundred and ninety-nine trees were treated in all, vary- 

 ing- in height from 20 to SO feet, and averag-ing about ()0 feet. 

 The cost of the arsenic used was $2.50; that of the labor employed 

 was about $9^); and the other expenses involved were $65, — making 

 the cost approximately 84 cents per tree. 



Only a small part of the infested trees were covered by this 

 operation, and many of those not reached by our parties were 

 nearly defoliated by the end of May. 



It was apparent October 2, when a visit was made to Jackson- 

 ville for an inspection of the elms, that most of the trees had sup- 

 ported the canker-worm attack without serious injury, only one 

 being- noticed which had apparently been killed by them. Others 

 somewhat heavily attacked had made no terminal growth of twigs 



