21 



garious habit of the larva', however, suggests another remedy which is 

 practical and very efficient if thoroughly carried out. This is the 

 destruction of the webs and the contained larva*, either by cutting off 

 the twigs which carry them and burning immediately, or burning the 

 webs without pruning. If this work be done properly and against the 

 early summer generation, the pruning method is unnecessary and inad- 

 visable. By the use of a proper torch the webs and the caterpillars 

 which they contain can be burned olt' at nightfall without necessarily 

 destroying the life of the twigs, and a second crop of leaves will be put 

 out a little later, so that the tree does not remain disfigured for any 

 length of time. A bundle of rags wired to the end of a pole and satu- 

 rated with kerosene makes a good torch for the purpose; or a porous 

 brick wired to a pole and saturated with kerosene answers the purpose 

 even better. Private persons will find this remedy sufficient. City 

 authorities should apply an arsenical spray. Collecting the cocoons in 

 winter maybe carried on simultaneously with the collection of the egg 

 masses of the white- marked tussock moth, but this, as well as other 

 community remedies, will be referred to at another place. 



THE RELATIVE IMMUNITY FROM INSECTS OF DIFFERENT VARIETIES 



OF SHADE TREES. 



As regards a number of the principal shade trees that are most com- 

 monly grown, there does not seem to be any great preference on the 

 part of the fall web worm and the tussock-moth caterpillar. If a moth 

 happens to lay her eggs upon or near a given tree standing in a row, 

 the species will naturally spread along the row before it will cross to 

 the opposite side. In this way erroneous ideas of the relative immunity 

 of trees have frequently been gathered. 



Taking the insect question as a whole, however, there is a decided 

 difference in the relative value of certain varieties. In December, 1893, 

 the Tree Planting and Fountain Society of Brooklyn asked a number 

 of experts to name for the use of the society nine of the most valuable 

 trees for planting in Brooklyn. Three of these trees were to be large- 

 growing, three medium-sized, and three small-growing varieties. 



The reply of Mr. B. E. Fernow, Chief of the Division of Forestry in 

 the United States Department of Agriculture, was comprehensive and 

 of great value. He tabulated nearly 50 varieties, analyzing their good 

 qualities under the different heads of endurance, recuperative power, 

 cleanliness, beauty of form, shade, leaf period, rapidity of growth, and 

 persistence, giving 3 as the highest mark for any one of these qualities 

 and estimating the value of a given tree by the total number of marks 

 given to it. This reply was printed and issued as a circular by the 

 Brooklyn society. Mr. Fernow made no specific rating for immunity 

 from insect pests, although in his introductory remarks he seems to 

 have included the insect question under the head of cleanliness. 





