352 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 6 



THE EFFECT OF TIDES AND RAINFALL ON THE BREEDING 

 OF SALT MARSH MOSQUITOES 



By P. L. BuTTRiCK, New Haven, Conn. 



Early in the Spring of 1912 the Civic Federation of New Haven 

 (Connecticut) raised funds for a campaign to control the mosquito 

 nuisance which every summer for many years has given the city a dis- 

 tinction second only to certain places in New Jersey. 



The chief species to be controlled was the banded salt marsh mos- 

 quito {Culex sollicitans Walk.). It was hoped to secure funds enough 

 to ditch all the salt marshes within five miles of the center of the city, 

 but as this was not done it was thought best to use some of the funds 

 to oil areas which could not be drained, thus temporarily keeping 

 down the numbers of the pest. 



Early in June the writer was placed in charge of this work, as well 

 as part of the ditching operations. The following is an amplification 

 of part of his report to the New Haven Anti-Mosquito Committee, 

 Inc., of the Civic Federation of New Haven, and is published with its 

 consent. Acknowledgment is due the officials of the Engineer Corps, 

 U. S. Army, stationed at New Haven, for permission to use govern- 

 ment tide gage readings, and for many valuable suggestions. 



The life history of the salt marsh mosquito was worked out some ten 

 years ago by the late John B. Smith and his assistants. The eggs 

 are laid singly on the salt marsh mud and lie dormant until covered 

 by water, either tide or rain. Thej^ then hatch in a few hours; and 

 in from six to fifteen days, according to the temperature, the pupae 

 transform to adults. After hovering about the marsh grass for a day 

 or two they migrate or are blown distances and invade summer re- 

 sorts, country sides, and cities, making life miserable for the inhabi- 

 tants. A few return to the marsh or remain in its vicinity and start 

 the next generation. 



The marshes where the salt marsh mosquitoes breed are usually 

 flooded at certain periods when the tides rise above the general level, 

 as usually occurs under the new moon. These are called the perigee 

 tides. Consequently, shortly after this period, a brood of mosqui- 

 toes is liable to emerge. At other periods when the tides are high or 

 when the marshes are flooded by rain other broods may be produced. 



In an oiling campaign a knowledge of the time of the perigee tides 

 is of the highest importance as it gives an opportunity for making 

 preparations for controlling the brood following it. To determine this 

 time, if possible, more accurately than can be done by calendar, a 

 copy of the tide tables of the United States Coast and Geodetic Sur- 



