356 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 6 



Observations at New Haven were made by combining the second 

 and third methods. 



By drawing a line across the tide chart at a height corresponding 

 to the height of the flood line it can be seen at a glance when flooding 

 will take place. Working charts used in the office also had the dates 

 marked on the horizontal ordinate and the height in tenths of feet 

 on the vertical ordinates at the beginning of each month. The moons 

 were also plotted. The hour of each high tide might be entered in 

 parenthesis after the proper point on the curve which for clearness 

 is enclosed in a small circle. By exaggerating the vertical scale the 

 differences in the height of the tide for different days are more clearly 

 brought out. 



The levels at which different local marshes about New Haven are 

 flooded vary. At South End a tide of 6.5 feet floods some of the 

 lower pools. Other marshes are not flooded until it rises over 7 feet; 

 6.8 feet seems an average and is used in the calculations for this 

 report. The average rise in New Haven harbor is 6.2 feet, the maxi- 

 mum about 8 and the minimum about 4 feet. The accompanying 

 chart shows the relation of the tides to the flood line for various years. 

 From them we see that occasionally the full moon tides rise above 

 the flood line, thus starting a brood of mosquitoes. It is also evident 

 that the perigee tides may not always rise high enough to start a 

 brood. If every perigee and full moon tide series flooded the marshes, 

 the 6 months from April 15 to October, — the mosquito breeding sea- 

 son for this locality, there would be 12, 13, or 14 broods possible, 

 depending upon the sequence of the moons. Probably this number is 

 never realized. The maximum number shown by the curves so far 

 plotted is 10. This number is indicated on the 1912 curve. The 

 minimum so far shown is 7 for the 1911 curve. Eight is probably an 

 average, curves for 7 years only being available. 



With our present knowledge of the time it takes mosquitoes to de- 

 velop, we can take the first day which a marsh is flooded in a series of 

 high tides and add the approximate number of days necessary for their 

 development and determine within a margin of a day or so when the 

 adults will fly. ■ 



It should be understood that temperature conditions, early or late 

 in the season, may be such that breeding is difficult, or impossible; 

 that heavy rains may flood the marshes at other times, producing 

 extra broods; or that winds and other causes may depress the tides 

 and cut out a small brood or raise them when they are near the flood 

 line so as to produce one not scheduled. 



The following shows how the August campaign was laid out on a 

 .single marsh. On Saturday, August 10, 1912, the maximum high 



