402 MOSQUITOES OF NORTH AMERICA 
has visited the marshes, has seen the excellent results of the work accomplished, 
and has watched the operation of digging the ditches. 
A bit of work, excellent in its results and very economical in its cost, in the 
way of the drainage of an upland marsh, is described by Doctor Smith in his 
report for 1908. A new normal school was about to be constructed on Montclair 
Heights, and there were swampy areas nearby which a committee of the State 
Board of Education considered to be dangerous as mosquito breeding-places. 
Doctor Smith caused an inspection to be made early in April, and found that 
there was a danger point in which not only the ordinary pool mosquitoes but 
malarial mosquitoes could develop. At a cost of $250, three thousand feet of 
ditching was placed or improved and all the surface water was drained to a 
culvert through a railroad embankment. The heavy rains of May gave excellent 
opportunity for testing the effectiveness of the work and no mosquito breeding 
was found there throughout the season. 
THE PRACTICAL USE OF NATURAL ENEMIES OF MOSQUITOES. 
Almost no practical use has been made artificially of the natural enemies of 
mosquitoes except with fish. It is true that about 1898 Mr. Albert Koebele im- 
ported into Hawaii from California a large number of western salamanders 
(Diemyctylus tortosus Esch.), which were liberated in the upper part of the 
Makiki stream in the hope of reducing the large number of mosquitoes breeding 
in small pools and in the taro fields. He kept two of these salamanders for 
several weeks in an open tank and they devoured all mosquito larve that oc- 
curred there; and while hundreds of the newly hatched mosquito larve could 
always be observed, none of them ever reached full growth. Whether these 
salamanders have increased in Hawaii and at present form an element in mos- 
quito control is not recorded. 
It has been suggested to breed mosquitoes of the genera Psorophora and 
Megarhinus, the larve of which are extremely voracious and feed upon the 
larvee of other mosquitoes; but Psorophora itself in the adult condition is an 
aggressive biter, so that to breed it for predaceous purposes is hardly to be con- 
sidered ; in other words, the remedy might prove worse than the disease. How- 
ever, Dr. Oswaldo Goncalves Cruz, Director-General of the Board of Health in 
Rio de Janeiro, told one of the writers in November, 1907, while on a visit to 
Washington, that Lutzia bigotii is used in Rio to destroy the larve of the yellow- 
fever mosquito. The Lutzia larve are exclusively predaceous, and this species 
is introduced in regions where the yellow-fever mosquito abounds, and its larvez 
destroy the other larve. 
For a long time fish have been used practically on a small scale. For example: 
“Tt was stated a number of years ago in Insect Life that mosquitoes were at 
one time very abundant on the Riviera in South Europe, and that one of the 
English residents found that they bred abundantly in water tanks, and intro- 
duced carp into the tanks for the purpose of destroying the larve. It is said 
that this was done with success, but the well-known food-habits of the carp seem 
to indicate that there is something wrong with the story.” (Mosquitoes, p. 161.) 
