392 



SCIENCE. 



[N. S. Vol. XVI. No. 401. 



ing. I secured, however, in some remaining 

 puddles a large lot of larvae and pupae and 

 placed these, in jars, under the covered tubs. 

 Adult mosquitoes were present in great num- 

 bers and, with pools so scarce, it was supposed 

 that the uncovered tubs would prove very at- 

 tractive. 



A series of glass jars was prepared with and 

 without water, with and without grass, and 

 captured females were introduced. In almost 

 every case eggs were found after twelve hours; 

 but as they were laid under all sorts of con- 

 ditions, and black mature, as well as white 

 immature, specimens occurred, it was obvious 

 that this was only the natural tendency of a 

 confined female to oviposit at all hazards. 

 But it was of real advantage in that it gave 

 us the egg so that it might be identified under 

 natural conditions. In color it is polished 

 black, pointed at both ends, almost perfect 

 spindle-shaped from one point of view, a lit- 

 tle curved or pod-shaped from another, half 

 turned over. In length it is less than one 

 millimeter. 



While all these preparations were made by 

 Mr. Dickerson, I explored the marshes round 

 about and found, to my surprise, that this im- 

 m.ense area which had been supposed to be the 

 very breeding stronghold of this species was 

 as a matter of fact perfectly safe. There were 

 no mosquitoes at all on these great marshes 

 and no larvae were in any of the ' salt ponds ' 

 formed by natural or artificial methods; not 

 until the edge of the upland was reached did 

 I find either mosquitoes or larvae. It goes 

 without saying that if this immense area of 

 salt meadow can be practically ignored in 

 mosquito extermination plans, we have made 

 a very long step toward the simplification of 

 the problem. 



Without going into details here it may be 

 said that the evidence from the tub experi- 

 ments was negative. Under none of the con- 

 ditions artificially presented to them did the 

 insects lay eggs. Yet egg-laying females were 

 present in abundance and some were sent to 

 New Brunswick by Mr. Dickerson about July 

 15. 



From the dissection of these specimens I 

 obtained the following record: 



No. 1. Black eggs 46, gi-ay eggs lY, white 

 eggs 101; total 164. 



No. 2. White eggs 117, and a little undigest- 

 ed blood in crop. 



No. 3. Black and gray eggs only, 148. 



No. 4. White eggs only, 135. 



No. 5. Black and gray eggs 47, white eggs 

 35 ; total 82. It is probable that this last 

 specimen had been ovipositing. 



July 20, when the tub experiments were 

 closed, all the evidence pointed to an oviposi- 

 tion on the sod, or in the dry bottom of old 

 breeding pools. Material from dried up pools, 

 old and recent, was obtained and examined 

 carefully in basins. A few eggs were found 

 almost everywhere, but not enough to make 

 it at all certain that these were normal points 

 for oviposition. Finally in our examinations 

 we reached the sods of long marsh grass, form- 

 ing the upper edge of a pool that was then 

 and for a time had been entirely dry. 



This sod was simply a mass of interlaced 

 roots and on the surface was a layer of soft, 

 black mud. In this mud I saw undoubted 

 mosquito eggs in such numbers that I washed 

 the surface into a basin and left the material 

 until next morning. ' Then the basin was 

 swarming with larvae and the eggs must have 

 been at the rate of from 50 to 150 on one 

 square inch of sod. 



After determining the place of oviposition 

 the next questions were under what circum- 

 stances do the insects hatch and how long may 

 they remain dry during the summer. 



Two sods approximating six inches square 

 were cut from the marsh and carried to New 

 Brunswick, July 21. One sod was placed in 

 a deep glass dish in the bottom of which was 

 half an inch of water. The sod was two in- 

 ches deep, so the surface was well above the 

 water, which was renewed from time to time 

 to keep it at about the same level. The other 

 sod was put into a porcelain evaporating dish 

 and left dry. It fitted loosely and air could get 

 on all sides and under it. Absolutely no mois- 

 ture was added at any time. 



July 31, ten days after the sod was taken, 

 a small piece — about two square inches — was 

 cut off late in the afternoon and the sur- 

 face mud was washed into a dish. Next morn- 



