Insect Hibernation 



443 



Brown-tail Moth, for example, prepare special winter retreats, 

 in the shape of silken tents, but such instances are not com- 

 mon. As a rule terrestrial larvae hibernate in holes in the 

 wood or in wood, and aquatic ones hide themselves in the mud 

 of streams and pools. 



" The first cold weather, after insects have entered into 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 ; its nutritive secretions 

 cease, no more food is required, 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 antennas resume their powers of extension, 

 and even the faculty of spirting out their defensive fluid is reacquired 

 by many beetles. But however mild the atmosphere in winter, the 

 great bulk of hibernating insects, as if conscious of the deceptive 

 nature of their pleasurable feelings, and that no food could then be 

 procured, never quit their quarters, but quietly wait for a renewal of 

 their insensibility by a fresh accession of cold" (Kirby and Spence). 



" It is probable that some insects of almost every order hibernate 

 in the egg state, though that these must be comparatively few in 

 number seems proved from two considerations : first, that the 

 majority of insects assume the imago, and deposit their eggs in the 

 summer and early part of autumn, when the heat suffices to hatch 

 them in a short period ; and secondly, that the eggs of a very large 

 proportion of insects require, for their due exclusion and the nutriment 

 of the larvae springing from them, conditions only to be fulfilled in 

 summer, as all those which are laid in young fruits and seeds, in the 

 interior and galls of leaves, in insects that exist only in summer, &c. 

 The insects which pass the winter in the egg state are chiefly such as 

 have several broods in the course of the year, the females of the last 

 of which lay eggs, that, requiring more heat for their development 

 than then exists, necessarily remain dormant until the return of 

 spring " (Kirby and Spence). 



The eggs are often attached to the bark of trees, where they 

 may be found arranged like a bracelet round a branch or in 

 compact masses, which vary according to the species. They 

 are often protected with a hard shell, or surrounded with a 

 warm coat of hairs. 



