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Marvels of Insect Life. 







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Photo by] [W. J. Lucas, F.E.S. 



A Grasshopper Nymph. 



A photograph of a skin cast on the assumption of the 

 winged condition. The pads which confined the un- 

 developed wiwgs will be seen standing out above the 

 middle pair of legs. 



How THE Butterfly gets its Wings. 



This dissection of a caterpillar of the large white butterflv 

 shows that the development of the wings is not so sudden 

 as is popularly believed. These are found in an incipient 

 stage in the caterpillar in the form of minute discs. In 

 its last skin they will be found just below the surface, 

 as indicated by the four crosses above. In the chrysalis, 

 as shown in a previous photograph, they come to the 

 surface. 



of bulk, we may borrow Newport's figures 

 relating to the caterpillar of the privet hawk- 

 moth. ^ When the caterpillar leaves the 

 rather large egg it weighs one-eightieth of 

 a grain. In nine days it has cast its second 

 skin, and weighs one-eighth of a grain. On 

 the twelfth day it casts its third skin, and 

 weighs nine-tenths of a grain. When it 

 moults for the fourth time, on the sixteenth 

 day, it weighs three and a half grains, and 

 six days later, when it appears in its last 

 skin, its weight has increased to nearly 

 twenty grains. But this last skin is very 

 accommodating, for this is the caterpillar's 

 period of most rapid increase. By the 

 thirty-second dav, when it has reached its 

 full-growth, its weight has increased to 125 

 grains. That is to say that in the thirty-two 

 days that have elapsed since it left the egg it 

 has increased its weight nearlv ten thousand 

 times ! 



From the foregoing it will be understood 

 that growth proper is restricted to the earlier 

 stages ; that when an Insect has reached the 

 winged state there is no further growth or 

 development. One frequently hears people 

 referring to a small fly as a young fly, and 

 some imagine that the small garden- white 

 butterfly represents a juvenile large garden- 

 white ; but these ideas are quite wrong. The 

 small garden-white can no more grow into a 

 large garden-white than a bull-frog can 

 develop into a bull. There is one insuper- 

 able bar in the case of Insects — with one 

 known exception, Insects are unable to 

 cast their skins after they attain to the 

 winged state. The exception is the may- 

 fl\' which invariablv, after it has left the 

 chrvsalis and expanded its wings, casts its 

 skin again, e\'en to the skin of the wings. 

 But apart from the may-flies it may be 

 stated with confidence that all the growth 

 and all the transformations have been got 

 over when the Insect first spreads its wings 

 for flight. 



Sjjliinx ligustri. 



