THE COMMON MOSQUITOES OF MINNESOTA 79 



even flower vases in a house, but will also oviposit in ground pools 

 if the water is sufficiently polluted. They prefer water which is 

 slightly or excessively foul, but we have several times taken the 

 larvae in water collected in cattle foot prints ; pools on the margin 

 of ponds and similar places. The size of the collection of water is 

 not essential, the prime requisite being that it remain permanent 

 long" enough for the larvae to mature. 



The wigglers will reach full growth in from six to seven days 

 if the temperature and food supply in the water is suitable. The 

 I)upa stage lasts for from one to three days, the entire life cycle may, 

 therefore, be passed in twelve days under optimum conditions. 

 Urood follows brood until frost appears. 



As the season advances the numbers increase until a locality 

 may be completely overrun with them. Rainfall is not favorable 

 to their development for, under such conditions, eggs and larvae 

 will be washed out and destroyed. Extremely dry weather also 

 is unfavoral^Ie, drying out most of the breeding places, except in 

 such places as sewers, where water collects and lack of rain prevents 

 their being washed out. 



The larva is pale yellowish in color and slender with the anal 

 siphon at least four times as long as wide and the sides slightly 

 swollen. The antennae rise from the sides of the anterior part 

 of the head and have the hair tufts beyond the middle point. 



The scales on the eighth abdomal segment are thirty-five to 

 forty in number, are well separated and form a low triangular patch 

 and each scale has a long fringe on the sides. The breathing tube 

 has twelve to fifteen spines in each row, each spine with three or 

 four long teeth. 



This species, while it does not occur in the extreme north of 

 the American continent, is probably found in every part of Min- 

 nesota where conditions favorable to its development exist. We 

 have taken it in the following places : 



Adults. 



University Farm — 23 to 2S of June. 1916. Near a pond. 



St. Paul— 24th June. VJKx 



Minneapolis — June 26th. 1916. 



Minneapolis — July 15, 1916. Near a marsh. 



