38 AGRICULTURAL EXPERIMENT STATION. 



On the Newark marshes the brood developed and early in May 

 spread inland, covering a territory even greater than the broods 

 of 1903, for now they were traced into the mountains north of 

 Paterson and directly west to Bemardsville, where in ordinary 

 seasons mosquitoes are practically unknown. 



The Raritan River brood reached New Brunswick May 12th 

 and the nights immediately following, and extended along the 

 valley to Somerville, following essentially the same track as in 

 1903. 



At Lahaway the first arrivals were noted May 17th, and by 

 the 24th the Pines were filled with them. 



For some reason no soUicitans developed on the Newark 

 marshes up to the middle of July and not a specimen was seen or 

 sent in by any correspondent from the towns where cantator 

 swarmed. On the Raritan meadows one section developed a 

 small brood in June, and this sent a few specimens to New 

 Brunswick a few days thereafter. 



South of Barnegat Bay soUicitans equaled cantator, but 

 developed a little later, so that the first arrival reached Lahaway 

 May 23d, and after a day of steady south wind and high tem- 

 perature the morning of the 29th found them present in force. 



Ciilex sylvestris, a breeder in fresh water swamps and marsh 

 areas, also flies for some distance from its place of birth ; but these 

 flights can scarcely be considered migrations, and as its breed- 

 ing places may be found almost everywhere, the species is really 

 at home however far it travels. This feature also makes it dif- 

 ficult to determine the actual source of supply when the insect is 

 troublesome. 



Culex perturbans is almost certainly a true migrant, from Mr. 

 Brakeley's notes ; but as we are yet unfortunately ignorant of the 

 early stages of this insect, this point cannot be considered proved. 



Culex tceniorhynchus develops with cantator and soUicitans 

 under the same conditions and migrates with them; but it does 

 not fly so far and is always so much less abundant that it needs 

 no especial account here. 



One noteworthy peculiarity in all the salt marsh migrants is 

 that the females are almost invariably sterile. I have examined 

 hundreds of soUicitans from Lahaway, from New Lisbon, from 

 New Brunswick, from the Orange Mountains and from num- 

 erous other points, and do not remember a single instance where 

 a specimen had developed ovaries. In cantator occasional speci- 

 mens with developed ovaries occur; but that is usually at points 

 not very far from the marshes. 



This fact points to the migration as due to a physiological 

 cause. It is not merely a wind-driven lot of specimens unable to 



