Culicidae 381 



The sand on the floor of the space under the aquarium (diurnal shelter 

 for imagines) is kept saturated with water the year around to increase 

 the humidity. Periods of excessively dry weather necessitate the flooding 

 of the floor of the insectary with water in the summer. By so doing it 

 has been possible to reduce the imaginal mortality which follows high 

 temperature and low humidity. When the mosquitoes are kept in lantern 

 chimneys or glass cylinders, considerable trouble arises from the con- 

 densation of moisture on the surface of the interior of the containers upon 

 their removal to warm air. In order to keep the mosquitoes from contact 

 with any solid surface on which moisture might condense, a type of cage 

 has been developed consisting of a bobbinet cylinder stretched on a brass 

 frame and tied in position. Only a very narrow ring of brass at each end 

 is exposed in the interior of the cage, and this is covered with a narrow 

 strip of filter paper which absorbs any condensing moisture. When cages 

 become soiled, the cylinders are removed, washed, starched, and stretched 

 over glass bottles to dry. Closure of the ends of the cages is effected 

 with squares of bobbinet secured by rubber bands. 



For the catching of individual mosquitoes in cages there has been 

 devised a special catching apparatus consisting of a test tube secured over 

 one tine of a spring forceps and a sliding lid placed over the other tine. 



When the mosquitoes are being removed from a cage with a catching 

 tube a special cover is placed over the open end of the cage. This is made 

 from a heavy rubber bathing cap consisting of two flat pieces of thin 

 rubber cemented along the crown. In the center of each flat piece a slit 

 is cut. These slits intersect at right angles and form a self-closing orifice. 

 The rubber band securing the bobbinet square over one end of the cage 

 containing mosquitoes is removed, and the bathing cap is laid over the 

 bobbinet with the slits over the center of the cage. The bobbinet square 

 is then drawn out from underneath and the cap is secured in place by the 

 rubber band. If the mosquitoes are to be transferred to an empty cage 

 with the catching tube, the transfer cage is similarly prepared. The cage 

 containing the mosquitoes is taken up in the left hand, with the cap- 

 covered-end toward the operator. The catching tube is held in the right 

 hand ; it is closed by pressure on the forceps tines, inserted through the 

 slit orifice in the cap, and opened. The open tube is then gently placed 

 over a mosquito resting on the opposite bobbinet end of the cage. The 

 mosquito will fly into the tube, and the open end may be closed by pres- 

 sure on the tines and the tube removed. If the mosquito is to be trans- 

 ferred, the closed tube is inserted through the orifice into the second cage 

 and is opened by decreasing the pressure on the tines. The mosquito is in- 

 duced to fly out by gentle tapping. If it is desired to kill the mosquito, a 

 pledget of cotton saturated with chloroform is placed over the mouth of 

 the tube. 



