WINTER NUMBER 41 
resting upon the moss. The minnows were all about the edges, 
but in some places the vegetation was too thick for even them. 
Wherever a little open water was found, there were the minnows 
but no mosquito larvae. They are very hardy and are entirely 
capable of freeing and keeping free from mosquitoes, any area 
of permanent water. They can be very readily introduced into 
ponds and aquaria that are not already stocked with fish of some 
kind. They are oviparous and breed all the year, so a few only 
would be necessary for a start. 
In the sink holes we have also the “‘goggle-eye”’ which is pre- 
daceous upon mosquito larvae. Four of these ate two hundred 
full grown larvae and ten Gambusia in four hours. Another rec- 
ord shows that they ate one hundred and fifty Culex and thirty- 
five Gambusia within forty-eight hours, and still another that 
they ate three hundred Culex in one hour. The sinks are well 
stocked with them. I have several times caught fifteen or twenty 
in an hour with a hook and line. In about one hundred specimens 
caught, this was the only species found. They do not seem to 
prey upon Gambusia naturally, for both are found abundant in 
the same sink. It was very fascinating to watch one of these 
fish, six inches long, chase a tiny wriggler. They seem very 
hardy and can be kept in an aquarium without much trouble. 
These and Gambusia keep the sink holes entirely free. I have 
several times during the year, carefully examined the sinks with- 
out ever finding a single larva. 
PREVENTIVES FOR MOSQUITOES 
This subject is naturally divided into two parts. Preventives 
for (1) Adults and (2) Larvae. There are endless protective 
fluids that have been recommended for protection from the bite 
of the adult. These usually contain some essential oil such as oi! 
of citronella, castor oil, pennyroyal oil, kerosene, oil of tar, etc., 
and many are undoubtedly repellant to mosquitoes. But all of 
them are more or less disagreeable to use and have to be fre- 
quently renewed to be effective, and, all in all, they are a poor 
makeshift. 
Screens and canopies afford great protection, but as ordinarily 
used do not keep out all of the mosquitoes. Examination of rooms 
in Thomas Hall has shown as high as thirty mosquitoes present, 
ten of which were Anopheles (crucians and quadrimaculatus). 
This is in spite of the fact that the dormitories have as good 
screens aS money can buy, showing how hard it is to keep mos- 
quitoes out if they are present. 
