SALLOWING. 243 



and Hereford producing sometimes large numbers. P. nibricosa is 

 also common, and oh, so red ! whilst T. (/racilis is scarce, appearing 

 usually later, and when the other species are almost over. The gem 

 of the umbrella's contents, however, is the black form of T. populeti, 

 whilst the bright-tinted P. piniperda, its beauties unrecognised until 

 one sees it alive, is sometimes accompanied by its grey-green aberra- 

 tion, which, considered on the score of its rarity, is a much greater 

 prize. 



Then there are the hybernators to be looked over. Hoporina 

 croceayo must be taken home, placed in a large glass jar, supplied with 

 a few twigs and dead leaves of the oak, fed with moistened sugar, and 

 then you will obtain a good supply of eggs. Xijlina aemlbrunnea, too, 

 must on no account be killed if a hen, nor Dasijcampa nihitjinea, for 

 both should be given every opportunity to lay their eggs, so that a 

 supply of moths may be obtained by the fortunate captor. A few 

 female Pachnobia leucof/rapJia, too, should be imprisoned. These must 

 be provided with a supply of leaves and old flower-stalks of plantain, 

 but otherwise may be treated as H. croceayo. 



Pages more might be written. We might tell you to get to the 

 woods early and kick the aspens to bring down the paired imagines of 

 Bi-ephos nutka ; we might suggest that you should search with your 

 lantern for the hundreds of Noctuid larvie that feed by the sides of the 

 woodland paths at dusk, or take advantage of the afternoon sun to 

 catch Daxijstoma salicdla as it flies by the hawthorn bushes, and we might 

 even hint with bated breath that now is the time to hunt iov Xijlomiges 

 conxj)icillaris, and that it occurs in this locality. But these are 

 nothing to do with "sallowing," and are such trivial matters that they 

 are scarcely worthy even of passing notice. 



The Resting Habit of Insects as exiiibited in tlie Plienomena of 

 Hybernation and Aestivation. 



By W. S. RIDING, M.D., F.E.S. 



It seems unfortunate that the word " hybernation " has been used 

 with reference to all the stages of an insect's metamorphosis whilst 

 the meaning is much limited when applied to ovum and pupa. 

 Applied to larva and imago, hybernation denotes a change from 

 activity to torpidity for a continuous period, assumed in a suitable 

 situation at the approach of winter, and followed by a return to 

 activity, its object being the preservation of the species ; but, applied 

 to ovum and pupa, owing to their nature, it can only denote a reac- 

 tion to the stimulus of cold. In the latter case, it is "a state," in 

 the former, " a selection of a state for a certain purpose." Kirby and 

 Spence drew this distinction between torpidity and hybernation many 

 years ago, though they did not apply it as above. If this be admitted, 

 it will conflict with the argument of Mr. Tutt, that, " as in tem- 

 perate regions, with few exceptions, all insects hybernate at some 



stage or other it is clear that the tissues of insects 



are capable at any stage of developing the habit of rest into a pro- 

 longed rest," In another place, Mr. Tutt seems to wish us to accept 

 this as a postulate, " it would appear that all living matter possesses 

 a capacity of assuming a resting state." In a general sense this 

 may be perfectly true, as all living matter seems to require periods of 



