86 



Infection probably occurs by ingestion of small ciliates, which might 

 readily pass through the gut wall into the body cavity and spread 

 all over the body. Although Anopheles hifurcatus, L., and Culex 

 pipiens, L., were kept in the same vessel as the infected Theohaldia, 

 they remained free from attack. 



Boyd (J. E. M.). The Botany and Natural History of the Dyke-Land 

 near Sandwich, Kent, as far as they concern Medical Entomology. 



//. R. A.M.C., London, xxxviii, nos. 1 & 2, Januarv and 

 February 1922, pp. 41-47 & 117-130. 



This paper contains a list of all the insects of medical interest caught 

 locally during the period from 1st April 1920 to 1st January 1921, 

 and includes Pediculus humanns, various fleas, the Tabanids, Haema- 

 topota crassicornis and Chrysops relicta, and the mosquitos, Anopheles 

 maculipennis, A. hifurcatus, Culex pipiens, Theohaldia annulata, 

 T. (Culicella) morsitans, T. (C.) fumipennis and Ae'des [Ochlerotatus) 

 rusticus. 



Anopheles maculipennis was far the more common of the two 

 Anophelines ; the larvae occurred in most of the dykes throughout 

 the summer, and the adults in cowsheds and stables throughout the 

 year. The first males were caught on 28th May and the last on 2nd and 

 10th November, which is later than is generally recorded. During 

 December there was a great decrease in the number of hibernating 

 females, and the destruction of the hibernating individuals must 

 necessarily reduce the number of mosquitos in a given area in the 

 following spring. In the laboratory at a mean temperature of 60° F. 

 eggs were deposited up to November. The 30th April was the earliest 

 date on which larvae were found in the dykes near the hibernating 

 places. The water in which they are found generally varies from fresh 

 to saline, but on one occasion they were found in a rain-water barrel 

 and in a solution of horse manure. Under laboratory conditions, eggs 

 laid in September hatched after two days, the larvae pupated after 

 another 22 days and the adults emerged after live days, giving a 

 total of 29 days. The usual period for development is from 18 to 

 20 days, the delay in this case being probably due to a limited food 

 supply. 



Very few adults of A. hifurcatus were caught. Most of the larvae 

 were found in dykes that had banks overgrown with weeds and in 

 which the water was almost stagnant in parts. The winter is passed 

 in the larval stage, which is apparently not affected by cold, as larvae 

 were taken in December from a dyke that was completely frozen 

 over. 



Adults of Culex pipiens were found throughout the year. The 

 first egg-raft was found 15th April. At an average temperature of 

 65° F. the eggs hatched in a day, the larval stage lasted 23 days and 

 pupation 26 days. Adults of Theohaldia annulata were also found 

 throughout the year. Whether only adult females hibernate is still 

 an open question, as larvae and pupae were found in the dykes up 

 to 14th January 1921. On one occasion a larva was seen feeding on 

 the roots of Azolla, and it was proved that males do emerge during 

 the winter months. The larvae live in the same dyke as A. hifurcatus, 

 and will also hve in dirty water, but not in such foul water as C. 

 pipiens. Many experiments on the effects of cresol, paraffin and 

 other substances on mosquito larvae were made. A 20 per cent, 

 saline solution was fatal to both larvae and pupae. 



