442. 



The Museum Gazette 



INSECT HIBERNATION. 



In our notes on " Anticipation of Winter" last month we 

 were obliged by necessity of brevity to almost omit from 

 notice the habits of insects. The following notes are intended 

 to supply in some degree the omission. 



The eggs of many insects are subjected throughout the 

 winter to extreme cold, which apparently does not impair their 

 vitality. 



Pupae are more abundant than eggs in winter They are, for 

 the most part, better protected against cold. Larvae occur 

 less frequently in a state of hibernation than pupae. The 

 majority are concealed in a simple hole or cranny. A few 

 prepare winter retreats. 



Many perfect insects hibernate, chiefly beetles, bugs, bees, 

 and flies, and a few lepidoptera. 



The winter sleep is usually spent in solitude. A few larvae 

 are gregarious, and some ants. 



Usually, in a species, one stage only of the four stages of 

 the life-history (egg, larva, pupa, and imago) is spent in 

 hibernation. A few species, chiefly butterflies, hibernate in 

 two, or even three stages. For example, the common Brim- 

 stone Butterfly passes the winter usually in the pupal state, 

 but the perfect insect hibernates in houses, outbuildings, &c. 



There are a few species which, strictly speaking, do not 

 hibernate. 



With a temperature below 45 0 F. the larvae and pupae of 

 many insects pass into a torpid state, the vital functions are 

 reduced to the lowest possible state, and so remain until the 

 advent of spring. We may instance the larvae and pupae of 

 flies. The angler, aware of this, buries the " gentles," as he 

 terms the larvae, m in a cold place during winter, and thus 

 ensures a supply of bait for the spring. 



There are several instances on record of larvae and pupae 

 reviving after being frozen so hard that they "chinked like 

 stones " when dropped into a glass. Some larvae, those of the 



