Mosquitoes in 
old Khartoum 
] )erris as a 
larvickle 
6G SANITARY NOTES. KHARTOUM 
epidemic came to an end. Curiously enough, adult mosquitoes were never seen at the 
British Military Hospital, and the nundier present must have been very small. 
Very occasionally other species are introduced, probably by the steamers. These are 
mentioned by Mr. King (see Report on Economic Entomology). 
There is still need for constant watchfulness, and it is worth remembering that both 
Sir Rudolph Baron von Slatin and Father Ohrwalder, of the Austrian Mission, testify to 
the fact that in the old days Khartoum was a perfect hot-bed of mosquito life. Indeed, the 
latter has stated that he has been driven to go and stand up to his neck in the Nile to 
escape the attacks of these voracious blood-suckers. In the Second Report one quoted 
Sohweinfurth as to the prevalence of malaria, and it is remarkable in what very tiny 
collections of water Pyretophonis costaJis will breed. The smallest of puddles amongst the 
stones by the river-edge, so long as it lasts for any time (and this is often the case owing to 
percolation through the sand), will serve the purpose, and such places are very apt to be 
overlooked. A good motto for the brigade would be, ‘‘ Do not put too much faith in the 
native inspector.” If well watched and controlled he does admirably, being remarkably 
quick at detecting the smallest larvie ; imt he cannot lie always trusted and must be 
supervised. 
A few experiments have been made in order to test the value of Iiern's nlii/uKisd. as a 
lai'vieide. In carrying out these 1 had the assistance of Mr. King. 
The roots of the plant were kindly supplied by Dr. Power, of the Wellcome Chemical 
Research Laboratories in London, but efforts to obtain other species of the plants from 
Kew Gardens failed. 
The following are the details of the tests made. In all cases the water employed was 
that in which the larvye were found, and controls were instituted ;— 
1. November -Ith, 190G. Three half-grovvu larvae of Calcj' fntiyans placed at 1 p.in. in an cninlsion 
consisting of 1 c..c. supernatant fluid from an alcoholic extract of Dcrris root (gni. 27 in hO c.c.) 
in l.oO c.c. of water. The emulsion smelt strongly of the drug and was of an opaque colour. 
ItesuU. No immediate effect and no effect after half-au-hour. Condition that night not noted. 
All the larvffi found dead on the morning of November oth, 190G. 
2. November 7th, 190G. Four half-grown Culex fatiyins larvse placed at 10.4.7 a.m. in loO c.c. of water 
containing 5 c.c. of above thud. Emulsion very opaque. 
Ucsiilt. No immediate effect. All dead in one-aud-a-half hours. 
3. November 8th, 1906. Four half-grown C'ulcx fntiyans larvae placed at 11..70 a.m. in 1.70 c.c. of water 
containing 1 c.c. of the shakeu-up Ilerris extracts, i.c. supernatant fluid and debris. 
Jicsa/t. No immediate effect beyond evidence of irritation, the larvae twisting and “biting 
their tails.” Two dead and the other two dying in one hour. All dead in one-aud-a-half hours. 
4. November 21st, 190G. One lively Cidcx faliyans larva placed in a .7 per cent, filtered watery extract of 
Dcrris uliyinosn, a dark reddish-brown liquid with a strong odour. The larvse died in 2.7 minutes. 
Eight lively half-grown t'ulcx fatiynns hirvse placed in 150 c.c. of water to which 1 c.c. of above 
watery e.xtract added. No immediate effect. 
.7. November 25th, 190(1. One lively t'liicr faliyans larva and one pupa phn'cd in a 2'.7 per cent, watery 
extract as above. 
Result. Larva dead after twenty-one hours; was alive after four hours. Pupa alive after 
twenty-four hours. 
G. November 27th, 190G. No. 5 repeated with same result. 
7. November 29th, 190G. Five lively C'ulrz faliyans larvie placed in 1 per cent, watei’y extract of powdered 
Derris root. 
Result. Moribund after two hours ; all dead in three hours. 
8. December 2nd, 190G. Four active Cutexfaliyans larvie placed in a 0’.7 per cent, watery extract as above. 
Rc.siill. No immediate effect. One found dead after four hours; others lively. All dead after 
twentj'-two hours except one, which, however, died after forty-eight hours. 
9. .lauuary l.st, 1907. Several larvie of t'idr.vfaliyans and one of /’yrclaji/iarus rostalis placed in a similar 
ll'n per cent, watery extract at 11.20 a.m. 
Result. All alive at 1.30 p.m. All dead the following morning. 
In order to see if the tannin in the Derris root had anything to do with its lethal 
action, two larvie and one pupa of Oiilex fatigmis were placed in a 1 per cent, watery extract of 
