674 



THE NATURE BOOK 



nymph rises to the surface and sticks its 

 back well out of the water. The skin soon 

 dries and cracks, and the perfect insect 

 emerges. It rests for a short time on 

 the old nymph-case, which serves as a 

 raft, imtil its \\ings have dried and fully 

 expanded, and then it flies away. Curi- 

 ously enough, while the male Gnat or 

 ^losquito is quite a harmless, inoffensive 

 creature, and sucks only the juices of 

 plants, the female is a most tormenting 



while those of the female are comparatively 

 simple in structure. 



The life-history of the EphemeridcB, or 

 Day-flies, is a very curious one, for they 

 are insects which last for the shortest 

 time imaginable in their perfect state. 

 Most fragile and delicate of creatures, they 

 float away in the air from off the water, in 

 which they have lived during the early 

 stages of their existence, to spend the 

 few brief hours of their perfect winged 



THE GHOST LARVA HAS A FORBIDDING- 

 LOOKING HEAD, BUT- 



TS GRACED WITH AN EXQUISITE FAN NEAR 

 THE EXTREMITY OF ITS BODY. 



and bloodthirsty insect, greedily sucking 

 the blood of man whenever she can get 

 the opportunit}'. As might be expected, 

 this di\ersity of food supply has led to 

 a very considerable modification in the 

 formation of the mouth-parts of the 

 male and female Gnats ; the stabbing or 

 piercing lancet of the female is very 

 highly developed. It is the female that 

 is the transmitting agent of disease from 

 man to man ; it sucks the blood, for 

 instance, of a man suffering from malaria 

 or yellow fever, as the case may be, and 

 so becomes infected and infective, for it 

 absorbs al(mg with the blood the parasite 

 that causes the disease, and introduces it 

 into the blood system of the next person 

 it bites. The difference in appearance 

 between the antennc-e of the male and 

 female Gnat is most striking ; those of 

 the male are beautiful plume-hke organs. 



life in graceful airy dancing and active 

 courtship. Truly they are the most 

 ephemeral of creatures ! 



The perfect insects are easily recog- 

 nised ; they have small heads, with large 

 compound eyes, and short awl-shaped 

 antenna; ; the wings are very delicate, 

 the front pair being the largest ; the 

 slender body is terminated by two or 

 three long-jointed bristles, and the legs 

 are very slender ; the mouth-parts are 

 often quite membranous in texture, for 

 the insect apparently takes no food 

 (luring the extremely short period of the 

 perfect stage of its existence. The most 

 familiar of the species, the May-fly, is a 

 brown colour, banded with yellow, and 

 has wings of a smoky hue with brown 

 spots. It is a wonderful sight to watch 

 the hundreds of these graceful insects, 

 on an early summer evening, performing 



