So N. J. Mosquito Extermination Association 



ably, the proportion under the house being reduced (to 36.5%) and 

 the proportion from the stable and inside the house being nearly 

 doubled (41.1% and 18.7% respectively). 



The two months with the highest rates were June and July, with 

 the July rate slightly higher than that for June, and with an average 

 of well over 400 Anopheles per collection for each of these months 

 for each tenant house and its out-buildings. There was some varia- 

 tion in the highest month in different years. In 1914 the August 

 rate was higher than for July and in 191 9 and 1920 June was the 

 highest month. For 1916 and 1920 the September rate increased 

 somewhat over the previous month. 



The rate for the five summer months from an average of all years 

 was 344 Anopheles for each tenant house and its out-buildings. 

 About 10% of these, however, were males, which subtracted from 

 the above figure gives a total of 310 female Anopheles from which 

 the average tenant family and his domestic animals are subject to 

 attack during each day of the five months. The daily rate is, of 

 course, a varying rate and the actual curve of density shows a rapid 

 rise from a low point in April or early May to a high point in June 

 or July and this is followed by a correspondingly sharp drop to the 

 latter part of September or the early part of October, as shown in 

 the accompanying chart (Chart i). 



Some explanation of the rate obtained per tenant home is neces- 

 sary inasmuch as the averages for one year (1920), the high mos- 

 quito year of the series, varied so much from the other years. The 

 record for the low year (1918) of the series could not be included 

 in the summary and the high year, when averaged with the other 

 years, about doubled the rates obtained, at least for the collections 

 under houses. The summer (May to September) rate for 1920 

 alone was 627.0 Anopheles per collection for underneath houses, 

 while for 1919 the summer rate was 96.5 and for 191 5 was 78.8 for 

 underneath. The summer rate for all years previous to 1920 (not 

 including 1918) was 11 5.6. On the other hand to include a low year 

 would not affect the final averages as much as might be expected. 

 For example, if the summer rate for 191 8 had been as low as 50, 

 for underneath the houses, to include this rate in the average for all 

 years underneath the houses would reduce the final figure only about 

 14% or from 232.8 to approximately 200. In this connection, too, 

 the facts must be considered that in the earlier years different groups 

 of houses were worked in different months and that the work as to 

 methods and technique was in process of development with con- 



