HYBERNA'HON OF INSECTS. 437 



feet state a ; Cinthia Cardui, Gonepteryx Khamni, and 

 some other species, usually in the pupa, but often in the 

 perfect state also; and Vanessa lo, according to the 

 accurate Brahm, in the three states of egg, pupa, and 

 imago 5 . It is probable that in these instances the per- 

 fect insects are females, which, not having been impreg- 

 nated, have their term of life prolonged beyond the 

 ordinary period. 



The first cold weather, after insects have entered their 

 winter quarters, produces effects upon them similar to 

 those which occur in the dormouse, hedgehog, and 

 others of the larger animals subject to torpor. At first 

 a partial benumbment takes place; but the insect if 

 touched is still capable of moving its organs. But as 

 the cold increases all the animal functions cease. The 

 insect breathes no longer, and has no need of a supply 

 of air c ; its nutritive, secretions cease, and no more food 

 is required; the muscles lose their irritability d ; and it 

 has all the external symptoms of death. In this state it 

 continues during the existence of great cold, but the 

 degree of its torpidity varies with the temperature of the 

 atmosphere. The recurrence of a mild day, such as 

 we sometimes have in winter, infuses a partial animation 

 into the stiffened animal : if disturbed, its limbs and an- 

 tennae resume their power of extension, and even the 

 faculty of spirting out their defensive fluid is re-acquired 

 by many beetles e . But however mild the atmosphere in 

 winter, the great bulk of hybernating insects, as if con- 



a Kyber in German Magazin der JEntomologie, ii. 2. 



b Ins. Kal. ii. 188. c Spallanzani, Rapports de I' Air, $c. i. 30, 



* Carlisle in Phil. Tram. 1805, p. 25. 



c Schraid in Illig. Mag. i. 222. 



