556 HYBERNATION OF INSECTS. 



hedgeliog, and others of the larger animals subject •to torpor. At first a 

 partial benumbment takes place ; but the insect, if touched, is still capa- 

 ble of moving its organs. But as the cold increases all the animal 

 functions cease. The insect breaths 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 antennae resume their power 

 of extension, and even the faculty of spirting out their defensive fluid is 

 re-acquired by many beetles.^ But however mild the atmosphere in 

 winter, the great bulk of hybernating insects, as if conscious of the decep- 

 tious 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. 



On this head I have had an opportunity of making some observations 

 which, in the paucity of recorded facts on the hybernation of insects, you 

 may not be sorry to have laid before you. The 2d of December 1816 

 was even finer than many of the preceding days of the season, which 

 so happily falsified the predictions that the unprecedented dismal sum- 

 mer would be followed by a severe winter. The thermometer was 46* 

 in the shade ; not a breath of air was stirring ; and a bright sun imparted 

 animation to troops of the winter gnat {Trichocera hiemalis), which 

 frisked under every bush ; to numerous Psychodce ; and even to the flesh- 

 fly, of which two or three individuals buzzed past me while digging in 

 my garden. Yet though these insects, which I shall shortly advert to 

 as exceptions to the general rule, were thus active, the heat was not suf- 

 ficient to induce their hybernating brethren to quit their retreats. Remov- 

 ing some of the dead bark of an old apple-tree, I soon discovered several 

 insects in their winter quarters. Of the little beetle Dromius quadri- 

 notatus, I found six or eight individuals, and all so lively, that, though 

 ren)aining perfectly quiet in their abode until disturbed, they ran about 

 with their ordinary activity as soon as the covering of bark was displaced. 

 The same was the case with a colony of earwigs. Two or three indi- 

 viduals of Drominus quadrimaculatus showed more torpidity. When 

 first uncovered, their antennae were laid back ; and it was only after the 

 sun had shone some seconds upon them that they exhibited symptoms of 

 animation, and, after stretching out these organs, began to walk. Close 

 by thein lay a single weevil (^Aiithonomus Pomornrti), but in so deep a 

 sleep that at first I thought it dead. It gave no sign of life when placed 

 on my hand, quite hot with the exercise of digging ; and it was only after 

 being kept there some seconds, and breathed upon several times, that it 

 first slowly unfolded its rostrum, and then its limbs. It deserves remark, 

 that all these insects, thus differently affected, were on the same side of 

 the tree, under a similar covering of bark, and apparently equally exposed 

 to the sun, which shone full upon the covering of their retreat.-^ 



> Spallanzani, liapports de V Air, (kc, i. 30. * Schmid in lllig. Mas- i- 222. 



' Since writing the above, I have had another opporlunily of confirming the observations 

 here made. The last week of January 1817, in the neighborhood of Hull, was most deli- 

 cous weather— calm, sunny, dry, and genial — the wind south-west, the thermometer from 



