SOLUBLE POISONS IN THE POISONED BAIT SPRAY. 1 53 



deed it may be, as will be noted later, that with ordinary spray- 

 ing of apple trees with a simple solution of arsenate of lead and 

 water for some other insects, such adults of the apple maggot 

 as chance to feed or drink at spots where poison has persisted 

 may be killed. The conclusion offered is that the adults are 

 not materially attracted to the bait, and that such sprays, or 

 any others so far devised, are without any adequate avail as 

 definite and sufficient protection of the fruit, in the absence of 

 other treatment." 



Investigations Here Reported. 



In our work in Maine not only were the entire orchards 

 sprayed but also apple trees in surrounding fields and dooryards. 

 An attempt was also made to control the apple maggot under 

 town conditions. In the season of 1914, different kinds and 

 amounts of poisons were employed in the bait in spraying the 

 various orchards and the apple trees in the residential section ; 

 whereas, in the season of 191 5, but one formula was used in 

 treating the same trees. Before giving the details of the work 

 in each season, the results of a number of preliminary experi- 

 ments will follow. 



DATES OF EMERGENCE OF FEIES. 



The dates of the first and last emergence of the pest have an 

 important bearing on when to make the first and possibly the 

 last applications of the poisoned bait spray. In the season of 



1914, the dates of emergence of the apple fruit flies were deter- 

 mined under orchard conditions ; whereas, in the season of 



191 5, similar records were obtained in the residential section of 

 Orono. Ground cages were placed on the sod or soil below 

 apple trees. Soil was banked and tamped around the bottom of 

 each cage to prevent the escape of any of the flies. During 

 the season the vegetation which sprouted beneath the cages 

 was cut with a sickle from time to time. Spiders and preda- 

 cious insects were removed from the cages as soon as they 

 were noticed. The records of the emergence of the adults, the 

 maximum and minimum temperature and precipitation in the 

 season of 191 5 are given in the following table: 



