40 



larviB began to appear, and, although the effects of the early spraying 

 Avith arsenate of lead were still noticeable on the leaves, the larva? 

 seemed to find areas that were not poisoned sufficiently to iirevent their 

 development. Another spraying was therefore given with Paris green 

 at the same strength as the last. A few larva?, a dozen or two to a tree, 

 still survived, however, and transformed at the base of the trees about 

 the 1st of July. Tliese were killed by the application of kerosene enjul- 

 sion to the trunk and about the bases, at a strength of 1 part emulsion 

 to 3 of water. 



The Department trees were thus carried safely through the first 

 brood of the elm leaf-beetle, covering a x^^i'iod of three months. In 

 the meantime many of tlie elms in the adjoining grounds of the Smith- 

 sonian Institution and at various places about the city had had their 

 foliage completely killed. The decided preference of the insects for 

 particular varieties of trees was frequently very noticeable, given trees 

 in many instances having their foliage entirely destroyed, while the 

 surrounding ones were untouched, presenting a very striking contrast. 



Cinder ordinary conditions the Department trees would have had 

 their foliage dead or dry by August 1, and the riddled and skeletonized 

 leaves would soon have fallen. The individuals of the second brood 

 first appearing would have had considerable difficulty in finding sub- 

 sistence on the few old leaves remaining, but the later appearing and 

 more numerous representatives of the second brood would develop on 

 the beautiful new spring-like foliage which the trees hopefully throw 

 out in late August and early September. The foliage of the Depart- 

 ment trees is now old and hard and more or less gummed with repeated 

 sprayings and accumulated dust, a condition which aftbrds consider- 

 abie protection, and up to the present time the beetles so far develoi)ed 

 of the second brood have not seemed to show any decided liking for 

 the trees, very few occurring on them. A careful watch will, however, 

 be maintained, and if there is the slightest indication of the appear- 

 ance of larvte another thorough spraying will be given. It is hoped, 

 however, though by no means certain, that the trees will now carry 

 their foliage safely through to the end of the season, with the gradual 

 assumption of the autumnal tints (a phenomenon which has not been 

 observed in Washington for many 3'ears), and finally shed it naturally 

 under conditions of frost and rains. 



To sum up, the protection secured for the Department's grove of elms 

 has necessitated two thorough sprayings for the adult beetles of the 

 first brood, two for the larva' of the first brood, the destruction about 

 the bases of the trees of the few larva* which succeeded in reaching 

 full growth, and the probable necessity of an additional spraying to 

 protect the trees from possible attack of the second brood of larva\* 



*Tho beetles did not further attack these trees, but elsewhere the second crop 

 of leaves followino- defoliation by tiio oarly brood of larv:i\ \Yas thorouuhly riddkd 

 •by the second brood of beetles and larva* as in former years. — C. L. M. 



(;OH)_>s\). L* 4 



