THE REASON WHY IN NATURAL HISTORY. 



497 



79. Why dots the caterpillar become torpid when 

 fasting into the state of the chrysalis t 



Because in all probability, where the difference 

 between the first and the ultimate form is con- 

 siderable, the organs of the insect having to 

 undergo great changes, it would suffer consider- 

 able pain. Torpor comes upon the insect, it is 

 thrown into a state similar to that ox a person 

 who has inhaled chloroform ; and after what 

 has, in all probability, proved a pleasant dream, 

 the insect awakes to find itself changed and 

 beautified. 



80. Why are the pupa of grasshoppers and other 

 insects, when about to undergo transformation, still 

 active and sensitive? 



Because, as there is but a slight difference 

 between the form which they have in the pupa 

 state, and that which they ultimately assume, they 

 do not require the state of torpidity to save them 

 from pain, nor to arrest their movements while 

 their organs are being changed. With them the 

 outer skin is thrown off, and they are then per- 

 fect insects. 



81. Why do caterpillars, when about to pass 

 through the chrysalis state, attach themselves to the 

 leaves of plants, etc.? 



Because they know instinctively that for a 

 time they will be unable to control their own 

 movements, and to avoid danger. They there- 

 fore choose secure and dry places, underneath 

 leaves, or in the crevices of old and dry walls, 

 and there they firmly attach themselves, to await 

 the time of their liberation. 



82. Why do insects attach their eggs to leaves, 

 ttc.t 



Because, as the eggs have to be preserved dur- 

 ing the winter, the insect attaches them to some 

 surface which will be a protection to them. 

 Generally speaking, the eggs are attached to the 

 permanent stems of plants, and not to those 

 leafy portions which are liable to fall and decay. 

 The spider weaves a silken bag in which it 

 deposits its eggs, and then it hangs the bag in a 

 sheltered situation. Nature keeps her butterflies, 

 moths and caterpillars locked up during the 

 winter, in their egg-state ; and we have to 

 admire the various devices to which, if we may 

 so speak, the same nature has resorted for the 

 security of the egg. Many insects enclose their 

 eggs in a silken web ; others cover them with a 



coat of hair, torn from their own bodies ; some 

 glue them together; and others, like the moth of 

 the silkworm, glue them to the leaves upon 

 which they are deposited, that they may not be 

 shaken off by the wind, or washed away by rain; 

 some again make incisions into leaves, and hide 

 an egg in each incision ; whilst some envelope 

 their eggs with a soft substance, which forms the 

 first aliment of the young animal ; and some 

 again make a hole in the earth, and having stored 

 it with a quantity of proper food, deposit their 

 eggs in it. 



83. Why do butterflies fly by day? 



Because they are organized to enjoy light 

 and warmth, and they live upon the sweets of 

 flowers which by day are most accessible. 



84. Why do moths fly by night t 



Because they are organized to enjoy subdued 

 light and cool air; and as they take very little 

 food during the short life they have in the winged 

 state, they find sufficient by night. Some of the 

 moths, like that of the silk worm, take no food 

 from the time they escape from the chrysalis 

 until they die. 



Because, also, they form the food of bats, owls, 

 and other of the night-flying tribes. 



85. Why are the bodies of moths generally covered 

 with a very thick downt 



Because, as they fly by night, they are liable 

 to the effects of cold and damp. The moths, 

 therefore, are nearly all of them covered with a 

 very thick down, quite distinguishable from the 

 lighter down of butterflies. 



86. Why do moths fly against the candle flame t 



Because their eyes are organized to bear only 

 a small amount of light. When, therefore, they 

 come within the light of a candle, their sight is 

 overpowered and their vision confused ; and as 

 they cannot distinguish objects, they pursue the 

 light itself, and fly against the flame. 



87. Why do insects multiply so numerously? 



Because they form the food of larger animals, 

 and especially of birds. A single pair of spar- 

 rows and a nest of young ones have been esti- 

 mated to consume upwards of three thousand 

 insects in a week. 



88. Why does the " death-watcn " make a ticking 

 noise t 



