44 THE ENTOMOLOGIST. 



times tried to breed it from the egg, and each time, in spite of 

 the stimuli of abundant warmth and abundant food freely ad- 

 ministered, the larvae have persisted in hybernating ; and had I 

 had only my own experience to draw upon, I should by this time 

 probably be dogmatically asserting that this was one of the 

 species which did not allow of artificial "forcing." But Barrett 

 writes as follows (' Lep. Brit.' viii. p. 18) : " On the wing in May 

 and June, and as a partial second generation, at the end of July 

 and in August, but Mr. A. H. Jones records that if fed up in 

 moderate warmth the second generation becomes complete, every 

 moth emerging in August or September." Two or three friends, 

 whose word I would trust as implicitly as my own, have confirmed 

 this last statement from their own experience ; and I am fain to 

 admit that mine has really been quite exceptional, albeit thrice 

 repeated. My moral is obvious. Do not generalize on slender 

 data. By all means record personal experiences, but use them, 

 not as a basis for too sweeping deductions, but simply as one 

 tiny contribution to be cast upon the common heap, from which, 

 at last, sound generalizations may be made practically without 

 fear of a " possibility of error." 



I have said above that an " Acidalia" "cannot hybernate 

 otherwise than as a larva." One would not be surprised there- 

 fore to hear that there was further a fixed age, or larval stadium, 

 assigned for this important period in its economy. There was a 

 good deal of talk in our entomological circles a few years ago 

 about this fixed hybernating stage and the certainty of death if 

 the stress of weather, or of failure of food, met the insect at any 

 other than the right period. But some data are already to hand 

 showing that the operation of natural selection is not always so 

 cruelly rigid as this, but — sometimes, at least — allows of a little 

 flexibility. Thus our " Wood Argus " butterfly and our common 

 " Brimstone Moth " can winter either as larva or pupa; Mr. K. 

 South once successfully hybernated four larva of Coremia uniden- 

 taria, a species which almost invariably hybernates as pupa ; and 

 in the Acidalice I have certainly had P. rusticata and almost 

 certainly also P. inornata hybernate in two different larval stadia. 



Where Acidaliid larvae may be found — or sought — I have 

 already indicated to a certain extent. They are all low-plant 

 feeders ; few, if any, are specialized to a particular plant ; and 

 therefore, theoretically, they might occur almost everywhere. 

 But there are few things more noticeable than their extreme 

 localization, and often they seem almost gregarious, so closely 

 does a particular colony keep to a particular hedge or bank. 

 There was a little bit of hedge opposite Highams Park Station 

 where, for years, the imago (and therefore of course the larva, 

 if one had searched closely enough) of P. interjectaria posi- 

 tively swarmed ; I have had seven in my net at once when 

 "dusking" along that hedge. And most entomologists have 



