II30 



Home Nature-Study Course. 



are two br-^athing tubes, which look like two ears, and when the pupa rests 

 at the surface of the water it remains head up so that these tubes may take 

 in the air ; at the end of the body are two swimming organs which are little, leaf- 

 like projections. At this stage the insect is getting ready to live its life in the 

 air, and for this reason probably the pupa rests for long periods at the surface of 

 the water and does not swim about much unless disturbed. It is a very strange 

 habit for a pupa to move about at all, as in other flies, butterflies, and moths the 

 pupa stage is quiet. 



When fully mature the pupa rises to the surface of the water, the skeleton 

 skin breaks open down its back and the mosquito carefully works itself out until 

 its wngs are free and dry, meanwhile resting upon the floating pupa skin, which 

 is indeed a frail bark, and the slightest breeze that ruffles the water is likely 

 to drown the insect before its wings are hard enough for flight. 



The reason why kerosene oil kills the insects when put on the surface of water 

 where mosquitoes breed is as follows : Both the larvae and pupae of mosquitoes 

 are obliged to rise to the surface and push the breathing tubes through so that 

 they will open to the air, and a coating of oil on the water prevents this and 

 they are suffocated. When the mosquito emerges from the pupa skin if it is even 

 touched by the oil it is unable to fly and soon dies. , 



Lesson XI 



MOSQUITOES • 



Purpose. — To teach the pupils to observe mosquitoes closely and 

 to be able to identify the comparatively harmless species of Culex 



from the dangerous species of Anopheles. 

 Material. — Mosquitoes should be killed 

 and studied through a lens or a compound 

 microscope. The mosquitoes resting on 

 the walls should be observed. 

 Obserz'ations by Pupils' 

 ( I ) . Has the mosquito feathery antennae 

 extending out in front? H so, what kind 

 of mosquitoes are they? 

 (2). Do the mosquitoes with bushy antennae bite? Do they sing? 

 (3). Are the wings of the mosquito spotted or plain? 

 (4). When at rest is it shortened and hump-backed or does it stand 

 straight out with perhaps its hind legs in the air? 



(5). What are the characteristics by which you can tell the danger- 

 ous Anopheles ? 



(6). Why is the Anopheles more dangerous than the Culex? 

 (7). Examine a mosquito's wing under a microscope and describe it. 

 (8). Examine the antennae of a male and female mosquito under 

 a microscope and describe the difiference. 



Antenna of male mosquito. 



