26 



CALIFORNIA STATE COMMISSION OF HORTICULTURE. 



sensory nerves, or those with which we feel and which convey impres- 

 sions to the brain, and the motor nerves, or those which receive im- 

 pressions from the brain. The one set enables us to feel, the other to 

 act. With tlie lower insects the brain and nervous system are very 

 simple, but in the higher orders it becomes more complicated, and is 

 evidence of the possession of much intelligent force. 



THE TRANSFORMATION OF INSECTS. 



One of the most peculiar and wonderful of natural phenomena is the 

 transformation or metamorphosis of insects — a process which, were it 

 not so common and going on under our observation every day, would 

 be unbelievable. If we did not know of it, and some traveler should tell 

 us that in a distant country he had seen animals that in one stage of 

 their existence were repulsive worms, and then became mummified. 



E - ^ 



FIG. 33. Eggs of various insects. A, butterfly, Polijijoiiia iiiterrogationis: B, liouse-fly, 

 Musca floiiiextica; C, clialcid, Bruchopliaguti fiincbris: D. butterfly, Papilio troilus; 

 E, midge, Cccidomyia trifoiii: F, heiuipteron, Triphleps insidiosus; G, hemipteron, 

 PodisnK ■■ipinosiis: H, fly, Drosopliila (uiipelophila. Greatly miignified. 



losing all semblance to themselves, being practically dead for some 

 time, and then broke forth from their mummy cases into the most 

 beautiful and )>rilliant creatures imaginable, far exceeding any other 

 animal in their beauty, we should regard him as drawing upon a very 

 vivid imagination and relating things that were utterly impossible. 

 Yet it is all true, and it is so common that it all passes under our eyes 

 without a thought on our part of the wonder of it. 



The insect passes through four stages: the egg, the larva, the pupa, 

 and the imago. The egg is the germ, the beginning, the contained 

 potentiality, which, under proper conditions, brings forth the new 

 being. The second stage, the larva, is the growing period. In this the 

 insect eats, increases in size, sheds its skin, or molts, several times, 

 until it ha§ stored up sufficient tissue for the final stage. But there is 

 an intermediate stage, one of remarkable change, in which the insect 

 ceases to be a mere eating, growing thing, and is transformed into its 

 perfect shape. This is the pupal form. At last the final change takes 

 place, and we have the new being in all its perfection. 



