INSECTS IN SAMOA. 2P>7 



Besides carrying the filaria that is responsible for so much trouble, Culex 

 fatigans also transmits the organism that produces dengue fever, a disease thai 

 causes an endless amount of suffering among the Samoans and frequently among 

 white men also. That the fever is caused bv the presence of some minute 

 organism, probably in the blood of the patient, there seems to be little doubt. 

 Just what the organism is has not yet been demonstrated. Dr. J. C. Parham, 

 Asst. Surgeon, United States Navy, has been studying the disease in Pago Pago 

 and believes that a certain coccus-like protozoan that he has found in the blood 

 of many patients is the causative agent, but his investigations have not yet been 

 completed Of the life-history of the parasite in the mosquito little is known, 

 but it seems that a period of a little more than three days must elapse after a 

 mosquito has bitten a patient suffering with the fever, before it becomes 

 infective. 



Unusual exposure to cold or wet weather or a weakening of the body from 

 any other cause is often followed by an attack of dengue. Recently all of the 

 Samoans were vaccinated against small -pox and many of those who suffered 

 most from the effect of the vaccination had to endure the tortures of dengue at 

 the same time. 



Culex fatigans is usually found breeding with S. fasciata near dwellings, but it 

 may be found much further away in the field or bush, breeding with S. pseudo- 

 scutellaris in any favourable place. I have found the eggs, larvae and pupae in 

 old watering troughs, stumps of. papaya trees, hollow places in logs, broken 

 coconut-shells, etc., more than half a mile from the nearest dwelling. I have 

 never been in the bush at night and do not know how bad a pest it is there. In 

 the house it begins biting early in the evening, often becoming very annoying. 

 Bed-screens are necessary at all times of the year. The mosquitos are persistent 

 in their efforts to get inside of the screens and readily find the smallest tear or 

 opening that has been left when the screen was tucked under the bedding. At 

 daylight they hide away in some darkened place around the bed or on dark 

 clothing that may be hanging in the room. I always collected numbers of them 

 in such places while making my daily morning rounds in search of S. fasciata. 



Stegomyia pseudoscutellaris is also very common about the house, biting freely 

 during the day and continuing its feeding later in the evening than S. fasciata 

 does. It is particularly troublesome in the early evening. It breeds wherever 

 suitable standing water can be found and is the most annoying pest in the field 

 and bush. It is a common custom simply to cut down a papaya tree when the 

 fruit is wanted. The trunk of the tree is divided by septa so that a deep cup is 

 usually left which soon becomes filled with water in which this mosquito delights 

 to breed. 



It is not definitely known that S. pseudoscutellaris transmits any disease, but it 

 is sometimes a host of the filaria that causes elephantiasis, and further studies 

 may show that it is concerned in the transmission of this disease and possibly of 

 dengue also. 



Another species of mosquito which we found on Upolu, while not as common 

 as the others, may prove to be of considerable interest. Dr. L. O. Howard 

 kindly identified this for us as Finlaya kochi, Donitz (F. poicilia, Theo.). The 



