2 BULLETIN 1093, U. S. DEPARTMENT OF AGRTCULTUEE. 



regard to methods of control which may 1:>e adopted in cases where 

 this pest becomes a menace to cranberry bogs.^ 



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 larvse, the prin- 

 cipal means by which both wet and dry cranberry bogs becom.e 

 infested. 



When trees are allowed to grow close to and overhang the l^og, 

 larvae 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 larvse 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. N. 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 tlie enlarged drawing of 

 the terminal bud of the ci-anberry plant ; and to C. E. Hood for the preparation of the 

 photographic illu-strations — all of the Bureau of Entomology ; to Dr. H. .1. Franklin, super- 

 intendent of the cranberry substation of the Mas.sachusetts State Experiment Station, 

 Wareham, Mass., for valuable information relative to the growth of the cranberry plant 

 and bog management ; and to .T. 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 up and management of the recording instruments. 



