2 BULLETIN 1083, U. S. DEPARTMENT OF AGRICULTURE. 
regard to methods of control which may be adopted in cases where 
this pest becomes a menace to cranberry bogs. 1 
ARTIFICIAL CRANBERRY BOGS. 
The locations in which cranberries may be grown vary considerably 
in regard to natural conditions. In Massachusetts, the State with 
which this investigation more particularly deals and in which more 
than half of the total crop is produced, the cultivated, or artifi- 
cial, bogs are constructed in locations where, perhaps, the cranberry 
once grew naturally, but not necessarily so. They are, however, always 
located in natural depressions of the land, varying in size from less 
than an acre to more than 100 acres, in natural swamps or bogs, 
in which the water table is constantly near the surface of the soil. 
To protect the plants against damage from frost or against insect 
injury, it has been found desirable to provide for flowing the bogs 
with water. Where this can be done the bog is called a wet bog; 
where not, a dry bog. Each has its advantages; but as a rule wet 
bogs are preferred. 
HOW BOGS BECOME INFESTED WITH GIPSY MOTHS. 
The topography of the cranberry-producing sections of Massachu- 
setts is characteristic of the glacial drift of Cape Cod. It is broken 
by low rolling hills, interspersed with bogs, ponds, and meadows, 
The uplands immediately surrounding the cranberry bogs, often 
from 10 to 50 feet high, frequently well wooded, furnish ideal condi- 
tions for wind dispersion of first-stage gipsy moth larvae, the prin- 
cipal' means by which both wet and dry cranberry bogs become 
infested. 
When trees are allowed to grow close to and overhang the bog, 
larva? may drop or spin down from the branches and reach the 
cranberry vines. When heavy infestations obtain in the wooded 
borders and are not destroyed, defoliation is likely to occur, and the 
larvae may crawl from the upland onto the bog in search of food 
and cause serious damage, as these large larvae feed upon both new 
and old foliage, even eating the bark from the vines. These are 
the three principal ways (wind, dropping, and crawling) by which 
1 The writer wishes to express his appreciation to A. F. Burgess, Dr. J. X. Summers, 
and I. T. Guild for their helpful suggestions and advice, which have added materially 
to the accuracy and value of this paper, and to the last for the map and upland trench 
drawings ; to F. II. Mosher for notes relative to the killing of the embryo in gipsy moth 
eggs by winter flooding of cranberry bogs ; to W. N. Dovener for the enlarged drawing of 
tbe terminal bud of the cranberry plant; and to C. E. Hood for the preparation of the 
photographic illustrations — all of the Bureau of Entomology : to Dr. II. J. Franklin, super- 
intendent of the cranberry substation of the Massachusetts State Experiment Station, 
Wareham, Mass.. for valuable information relative to the growth of the cranberry plant 
and bog management ; and to J. W. Smith, meteorologist in charge of the U. S. Weather 
Bureau at Boston, Mass., and his assistants for information relative to wind currents, 
temperature, and the setting np and management of the recording instruments. 
