332 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 15 



The Colombia remained at Baltimore four days and began the return 

 trip on January 12, 1922, and left Norfolk, Virginia, on the 14th. Arsen- 

 ical syrups, formulas A and B, were placed in all rooms on that day though 

 no ants were seen. Indeed they did not appear till we left Havana, 

 Cuba and were in the Caribbean Sea January 18th. The attack was 

 light and easily controlled with the formula C powder. On the night of 

 January 20th a vicious attack by the ants were reported in three rooms 

 directly across from the engine room. These rooms were visited at 

 midnight and it was found that the ants were attempting to establish 

 formicarys in the beds. They were carrying pupae to these beds in great 

 quantity. A liberal use of the powder quickly relieved the situation. 

 The following day the cause of the migration was discovered. A boy 

 had been sent up the ventilator shaft connecting with the engine room. 

 The boy's visit was for purposes other than ant hunting but he got into 

 a well populated formicary in the shaft. He came out in a hurry, literal- 

 ly covered with ants. He was severely bitten. This disturbance had 

 undoubtedly made the ants uneasy, hence the attempt to establish new 

 formicarys. Owing to the necessity of keeping these ventilators in 

 active use while the engines were going, drastic treatment of them had 

 to be put off till January 23d while the ship was lying at the dock at 

 Cristobal, Canal Zone. Here we had the outside ends of the ventilators 

 covered with canvas and then ran live steam into them for an hour. 

 Vast niwnbers of ants were destroyed by this action. From January 24th 

 on, only occasional small straggling groups of ants were seen and no com- 

 plaints were registered. The last ants were seen as we left Manzanillo, 

 Mexico, northbound on February 3, 1922. We here experienced cold 

 weather conditions which continued until our arrival in San Francisco 

 on February 10th. Careful inspection and search failed to disclose a 

 single ant. They undoubtedly had again gone into donnancy and 

 so ended the ship board ant campaign. 



The frequently recurring dormant periods seem to stimulate these 

 ants to very active work when warm conditions supervene. In the 

 period that this study was made, fifty-eight days, the ants were dor- 

 mant three times and the time devoted to reproduction and the gather- 

 ing of stores was brief as compared with the same activities under normal 

 conditions on shore. Certain it is that these ants were numerous, active 

 and vicious. 



In view of the seriousness of the pest on shipboard, the money loss 

 due to their depredations on stores and the extreme discomfort their 



