CONTROL OF GIPSY MOTH BY FOREST MANAGEMENT. 19 
the gipsy moth,” the percentage of white oaks has been selected as a 
basis of comparison for the six stands now under consideration. 
The percentage of white oaks present gives a natural and definite 
basis of comparison which has a direct bearing upon both manage- 
ment and moth control. : 
With the exception of tamarack, there are no conifers among Class 
I trees (favored food of the caterpillar). As there is no tamarack on 
any of the lots now under consideration, the retention of conifers is 
an important factor in moth control in these stands. In any stand 
the leading species—that occurring in the greatest number—requires 
careful consideration both as a food plant and as a forest tree if 
success 1s to be expected. The presence in large humbers of young 
growth of species desirable from both viewpoints is also important. 
This brief statement by no means includes all factors which must 
be considered, but the suggestions given below are based upon them 
and upon markets as controlling factors in management. For con- 
venience of reference four of the important factors are summarized 
in the form of a table which follows: 
Some controlling factors in management. 
Number 
} of gipsy- 
Stand at— nie Conifers. Leading species. pees 
per acre 
in 1913. 
Per cent. | Per cent. Per cent. 
ID OVET MASSE iiss vem apie LUM iae so is Mama uw ale) 38 3 | Red oak. ... 45 15,000 
SEG COMMUN ET CGA ce taitiee nib sande ne ee MiNi MNS eV Ry Vai 30 ar ectos Goeth 31 949 
WWiareh amr yiMia‘ge een t yn 7a Lnycie seo A aap ial eae en aN) 0 21 16 | Scarlet oak.. 54 12 
INTO ROTORS Stee ANTS sical ee Ne Wb Ne ye en a 10 9 | Chestnut.... 52 4,374 
PRIMES DUTY MASSU Misael es eye ree ek Aen CI 5 41 | White pine.. 28 590 
INortheBerwacks Meso Sy i eee a ei HA a eae Seah 4 | Beech......- 45 1 
TREES WHICH CONTROL. 
From the list of 150 food plants of the gipsy moth, published in 
Bulletin 250, there were selected and considered in Part I all native 
or naturalized trees which might be found in woods in the infested 
region. Seventy-five species are included, and the list is given on 
pages 8-10. 
When sufficiently numerous in a stand these would be leading spe- 
cies, as that term has been defined above, and by that fact alone they 
might become controlling factors in management, but many trees 
in the list occur so infrequently or are so small that their presence or 
absence in a stand would have no controlling effect upon the form 
of management to be practiced. 
Of the whole 75 species only 18 have silvical characteristics which, 
apart from any considerations of commercial value or of moth con- 
1See Appendix, p. 51, 
