370 SANITARY ENTOMOLOGY 



To prevent spread of fleas from regions where plague is present, care 

 should be taken not to allow rats and mice to gain access to packed 

 materials, and fumigation of clothing and other articles should be prac- 

 ticed en route or at destination. Precautions against the transference of 

 rats from ships to land or from the docks to ships when in port are 

 very essential. All boats should be kept at least four feet away from 

 the docks and all hawsers should be provided with rat guards. These 

 are metal discs at least two feet in diameter fastened to the rope between 

 the ship and dock. Gangplanks should never be left down day or night, 

 except when actually in use and care should be taken not to transfer 

 rats with cargo. This is often very difficult, if not impossible. 



Fumigation of ships when entering port is, of course, the safest plan 

 to follow, especially if they have touched ports where plague may be 

 present. At the present time this is practiced in nearly all the important 

 ports of the world. Sulphur dioxide applied under pressure by the so- 

 called Clayton method, and hydrocyanic acid gas are employed. This 

 fumigation, if properly done, accomplishes the destruction of the rats, 

 fleas and other life aboard. The hydrocyanic acid gas appears to be 

 giving best results and danger of damaging cargoes is lessened. 



Since fleas are largely attracted to moving objects it is possible to 

 collect great numbers of them by allowing men with their legs wrapped in 

 paper treated with tanglefoot to walk about over the infested area. Where 

 fleas are less abundant, and especially in places where plague is suspected, 

 the use of animal hosts to collect the fleas may be employed. Guinea 

 pigs, white rats, or rabbits may be used for this purpose. After being 

 in the infested premises for some time, the fleas may be killed by placing 

 the trap animal in a jar and applying chloroform and when the 

 anesthesia is complete, the fleas will either drop off or remain on the 

 surface of the hair where they can readily be picked off^ and placed in 

 containers before reviving. Of course the animal may be treated with 

 kerosene emulsion or other insecticides. The eff'ectiveness of animals as 

 traps varies with the species of fleas concerned. The Indian rat fleas and 

 European rat fleas do not go freely to guinea pigs but are caught in 

 great numbers on tanglefoot on man. The squirrel flea will go to guinea 

 pigs very readily. 



Dr. Hindle has described a flea trap used in China. It consists essen- 

 tially of a cylinder covered with tanglefoot, and protected against stick- 

 ing to objects by an outside cylinder wath openings to allow the fleas to 

 strike the sticky surface. This can be rolled about on the floor of the 

 infested rooms. 



Medical Treatments for Flea Attack. — Flea bites seldom need medical 

 treatment. However, some people are so susceptible that irritation and 

 itching follow the bites, and some develop ulcers. The use of disinfectant 



