330 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 15 



numbers and had caused much discomfort to all hands. Careful ques- 

 tioning failed to bring out any clear description of the ant so no definite 

 fact was available on which to base a theory of control. In view of the 

 conditions present it was thought best to provide poisons to meet 

 various situations as they might arise. Beside a niunber of non-proprie- 

 tary insecticides a quite complete stock of proprietary ant poisons was 

 obtained and rather fully equipped for a thirty day campaign we left 

 San Francisco on December 12, 1921, as scheduled. Cool weather con- 

 ditions prevailed until December 14, 1921, when under the warmer con- 

 ditions experienced at San Pedro, California, ants began to appear. 

 These ants were small, not more than three millimeters in length, and 

 were very active. They were later identified by Dr. W. M. Wheeler, 

 Harvard University, Bussey Institution for Research in Applied Biology, 

 as follows: "The ants. . . .are specimens of Monomorium- {Parholco- 

 myrmex) destructor Jordan. The species is originally Indian and has 

 long been known as an unpleasant house ant and is even suspected of 

 carrying the plague. During more recent years it has become tropicopol- 

 itan It is interesting to find it on a ship, and of course one would ex- 

 pect it to become active while the ship was in the tropics."^ 



From San Pedro southward to the port of Manzanillo, Mexico, well 

 within the tropic of Cancer, the ants increased in numbers and were ex- 

 ceedingly troublesome in the passengers' rooms and in the steward's 

 crew quarters in the waist of the ship alongside the engine where the heat 

 was greatest. They were also very troublesome in the pantries, galleys 

 and store rooms. Experiments with various poisons and contact insec- 

 ticides were begun as soon as the ants began to appear at San Pedro. 

 Capsules containing arsenical poisons made up as per formulas A and B, 

 (last page) were placed, opened, wherever ants were seen. Sponges 

 moistened with the same poisonous syrups and contained in perforated 

 tins were also freely used. These capsules and tins were inspected daily 

 end it was found that only occasional ants visited them. Indeed it may 

 be stated that the arsenical poisons, as used, proved to be only a partial 

 control and not quick enough to afford the necessary relief to passengers 

 and crew. Complaints were made and no doubt the reports as to the 

 viciousness of their attack on himian beings were correct. They would 

 find their way in small or large niimbers into the beds and their bites 

 were very painful. Proprietary ant poisons were used dusted into the 



^The determination was secured through the courtesy and help of the Division of 

 Entomology and Parasitology, University of California. 



