68 NOTES ON THE "SCOTS GRAY " MOSQUITO 



bottom of the vessel or pool upon which they are placed. If 

 they lie some time a flocculent algfB of the Nostoc variety at- 

 taches itself, and helps to anchor them to any object in close 

 proximity. The period of incubation depends chiefly upon the 

 temperature, and is hastened during close damp thundrous 

 weather. The eggs of the ordinary kind may hatch in thirty-six 

 hours, but these require under favourable circumstances, seven 

 days. One striking peculiarity is, that if the temperature falls 

 below 70deg. Fah. in this latitude, they may lie in the water 

 for many months, but still retain their vitality, and emerge 

 when circumstances are more favourable to their incubation. 

 On February 24th I got a batch and placed them in a cage ; 

 they deposited a large number of eggs the same night. On 

 Jrlarch 5th, two larvas were seen, on the 7th another, and on the 

 8th two more. Then on May 7th twelve emerged, and the next 

 day six more, and on the 10th another half-dozen ; a lull then 

 took place, and on October 31st one appeared. November 6th 

 six more, on the 29th nine came out ; December 4th, one ; and 

 on the last day of the year, a swarm of one hundred broke cover. 

 Then one more was seen on January 16th. These all came from 

 the eggs of the batch laid on February 24th. They were kept 

 in a case to which no insects could have access, so that there 

 could be no possibility of the experiment being vitiated by other 

 eggs being deposited there. The last one, therefore, was nearly 

 eleven months' old before it appeared. 



Thp: Larva 



when ready, by its internal straggles bursts the shell at a point 

 about one-third from the end, as is seen in fig. 2, where one is 

 partially extruded. It i.s strong and lively, and easily 

 distinguished by its colour and appendages from other kinds. 

 Fig. 3 is a photo, of a newly-born baby. The head and the tips 

 of the tracheal tube are black, the thorax white, and the 

 abdomen yellowish, and on the vertex of the head is a large 

 dark spot, as large as and equidistant from the eyes. 



The mouth brushes are black and set horizontally. Four 

 very long natatory bristles project from the last section in a 

 line with the body. A common practice is for them to use the 

 tracheal tube as a pivot, and by the aid of the mouth brashes, 

 whirl round in a circular direction on the surface of the water. 

 Their position is usually horizontal in this first stage. 



