28* 



LItfE HISTORY AND HABITS. 



to it are known ; the pupa is commonly in the ground in an earthen cell, 

 or in the burrow of the larva or in a tough case on a plant. Many have 

 naked pupse fastened to plants. The cases they make are of twisted fibres 

 (fig. 37) as in the Palm Weevil (fig. 247), of excrement (fig. 36) as in 

 some leaf beetles and weevils, or of secretion produced by the larva (some 

 weevils). The butterflies have suspended pupse, fastened to plants, often 

 of peculiar form with resemblances to torn leaves, etc. Moth pupae are 

 usually in cocoons formed of silk alone (fig. 39) or with hairs (fig. 35) 

 or are found in the 

 ground, on plants, in 

 the larval burrows, etc. 

 The silk of commerce 

 is produced from the 

 cocoons of various moths, 

 and almost all cater- 

 pillars can produce silk 

 throughout their larval 

 life, using it for a variety 

 of purposes. The pupa 

 of Diptera is to be found 

 in the habitat of the 



FIG. 38. 

 Butterfly Chrysalis., showing the thread ly ^vhich it is 



fixed to tie plant. 



larva, without covering as a rule. Insects display great ingenuity in the 

 devices they adopt for the protection or covering of the pupa. The pupal 

 period is commonly short, a few days in flies, a week to ten days in many 

 butterflies and moths (unless hibernating), about the same in the known 

 Hymenoptera and in some CoJeoptera. It is 

 however much prolonged in some Cvleoptera 

 and may be very long in all groups if hiberna- 

 tion is taking place in the pupa, as it often does. 



In some Coleoptera, the imago emerges 

 from the pupa and undergoes a further 

 resting period before leaving its hiding place. 



We may here mention the flies which 

 pass through no larval period, but are pro- 

 duced by the parent as full grown larvae^ 

 which at once pupate. The best known of 

 these are the Horse and Cattle Flies (fig. 320, 

 page 265) which live upon the blood of birds 

 and mammals. This abnormal life history 

 is possibly an adaptation to the semi-parasitic 

 life of the imago, 



FIG. 39. 



Male (above') and Jemale Moth 

 with Cocoon (lelow). 



