142 MOSQUITOES OF NORTH AMERICA 



out on the surface of the water behind her, parallel to each other, not crossed as 

 some observers state. A single row of creamy white eggs had been laid flat on 

 the surface of the water and were kept in position by the two hind legs. . . . 



" When the first row of eggs was completed she laid another row on the top of 

 it, and then another on the top of that, and so on until the raft was finished. 

 Then by a movement of the hind legs she tilted the raft so that the eggs stood 

 on end." 



In the genera Culex, Culiseta and Mansonia the egg-mass rests upon the sur- 

 face of the water. The mass has a certain repellant quality, inherent, it seems, 

 in a covering of delicate air-cells on the under surface. In the genera Urano- 

 tmiia and Lntzia the egg-boat is in part submerged, only the upper part of the 

 eggs protruding from the water. Thus, Dyar states that in the egg-boat of 

 Uranotcenia sapphisms the middle eggs are nearly half submerged. In the 

 case of Lutzia higotii, as observed by Jennings, the egg-boat is in large part 

 submerged, only the apices of the eggs protruding above the water. The eggs, 

 which are arranged in a double row, are remarkable in coloration ; the submerged 

 portion is pale yellow with a golden luster while the exposed part is pale blue. 



The number of eggs and their mode of arrangement varies for the species, 

 and to a certain extent within the species. The egg-raft of Lutzia bigotii, just 

 mentioned, is composed of about fifty eggs arranged in a double row. The eggs 

 of Mansonia fasciolatus and M. arribalzagce are arranged in a long, ribbon-like, 

 double row with a gentle convexity upon the under side. Goeldi states that 

 there are about 60 eggs in these egg-rafts but his reproductions of photographs 

 of such egg-masses show from 70 to 80 eggs in a row, therefore 140 to 160 in the 

 entire mass. Our Mansonia perturhans forms an egg-raft similar to that of 

 Culex, that is, with tlie eggs in a number of rows forming an elongate mass and 

 the under surface of the mass convex. In Culex, Culiseta and Uranotcenia the 

 egg-masses are elongate, and, on account of the convexity of the lower surface, 

 the sides are somewhat upturned. 



Few exact data are available as to the number of eggs laid, even for the com- 

 monest species. With reference to the common house mosquito, Culex pipiens, 

 250-300 is generally given as the normal number, a statement to be traced back 

 to Eeaumur's work. Our American observations are unsatisfactory, as a num- 

 ber of species have undoubtedly been confused under the one name. Davis, in 

 Illinois, found the number to vary from 120 to 309 in a count of ten egg-boats. 

 Smith states that normally the number of eggs laid by Culex pipiens in a single 

 raft is about 400 but that if the female is disturbed in the process there may be 

 two or more smaller rafts formed. Goeldi (at Para), in a count of two egg- 

 masses of Culex quinquefasciatus found 225 and 270 eggs respectively and his 

 pictures show that they are arranged in from 9 to 11 rows. C. S. Banks, with the 

 same species before him in the Philippines, found the number of eggs from 180- 

 350, arranged in from 6 to 9 rows. In Culex territans two egg-masses counted 

 by Knab contained respectively 105 eggs in six rows and 132 eggs in eight rows. 



A singular departure in the mode of egg-laying, or rather in the character of 

 the eggs, has been recorded by Busck in Culex jenningsi, and this is probably 

 shared by other bromelia-inhabiting species of Culex. In this case the eggs are 



