October, '22] clarke: ant control on ships 331 



beds and were found to be fairly effective in destroying ants in these 

 situations. All of these proprietary materials had a tendency to take up 

 atmospheric moisture and to become lumpy. As the voyage continued 

 further southward in the tropics atmospheric humidity became greater 

 and distribution of these remedies because of the limipiness became more 

 difficult. As these control agents were placed in the beds the odors 

 coming from some of them were objectionable. Also in some cases the 

 control was almost as bad as the ant bites inasmuch as the powder was 

 very irritating to the skin and mucous membranes of humans. It was 

 soon evident that a powder should be developed that was non-absorb- 

 ent of moisture, practically odorless and, further, non-irritating. 

 After considerable experimenting such a powder was developed, its 

 component parts being sodiimi flouride, pyrethrum (ground stems and 

 flowers) and starch. Formula C, last page, gives the make up of this 

 powder in detail. It was found to be a very efficient insecticide and 

 numerous observations showed that death of the ants followed in from 

 twenty to thirty seconds after the material had touched them. In 

 addition to its killing power the powder met the non-moisture absorbing, 

 non-odorous and non-irritating conditions before mentioned. By the 

 time the ship arrived at Manzanillo, Mexico, December 19,1921, the 

 overwhelming strength of the infestation was shown and the efficacy of 

 the formula C powder demonstrated. The powder was dusted freely in 

 passengers' rooms, steward crew's quarters, pantries, on grated floors of 

 galleys and in the store rooms. The ants were well in control through 

 this treatment by the time the ship arrived at San Jose de Guatemala, 

 December 23d. From this point on, though tropical weather conditions 

 with much humidity prevailed, through the Canal and to Havana, Cuba, 

 but few ants were seen and no complaints from either passengers or 

 crew were registered. The few ants that did appear in the pantries and 

 syrup lockers were quickly disposed of with the formula C powder. 

 From Havana northward past Cape Hatteras to Norfolk, Virginia and 

 Baltimore, Maryland, cool to blizzard weather was experienced. The 

 ants disappeared entirely, going into dormancy because of the cold and 

 very careful search failed to disclose their nesting places. 



It is interesting to note that but one formicary was found on the 

 outward trip. This was a small one comprising but a few hundred in- 

 dividuals and was located in a fairly large pot of earth in which was 

 growing an ornamental plant. This was in the dining saloon and its 

 removal and destruction resulted in nearly complete relief from the pest 

 in that part of the ship. 



