184 Mosquitoes 



fourteen to one hundred and ninety-four days after 

 laying, and the eggs will resist drying. The period 

 of hatching of the ova of the same batch may ex- 

 tend over forty days. This species evidently 

 winters in the egg stage. The larvas devour 

 Euglena, also young Spirogyra. They have a 

 habit of sailing about by means of the mouth 

 brushes, from the surface to the bottom, proceeding 

 from the top at an angle of about 45 or so. When 

 they reach the bottom they will seize a large bunch 

 of Spirogyra and again float upward, shaking the 

 bunch and breaking it to bits. Unless disturbed they 

 do not jerk about. They stay below for long periods, 

 sometimes for an hour. This species cannot be con- 

 sidered as a city nuisance, but in the woods, in the 

 south at least, it is certainly very troublesome. It 

 ranges from New York to the Gulf, and westward to 

 Indiana, being also a common South American form. 

 Janthinosoma varipes. — This is another inhabit- 

 ant of clear wood pools and appears to be southern 

 in range. We occasionally found them, though not 

 abundantly, in the willow pool on the campus. They 

 are sometimes locally plentiful for a short time, but 

 cannot be considered a nuisance. The adults were 

 taken between April 18 and October 18. They 

 bite sometimes twice, usually once, before laying the 

 first batch. They generally deposit one or two 

 batches, averaging about 60 eggs each. One speci- 

 men made a record, laying eight batches of from 

 51 to 104 ova, 578 altogether, biting nine times. 

 The first clutch is laid three to eight days after the 

 first feed, generally three or four days. In captivity 



