BOJIBYX QUBRCUS AND BOJIBVX CALLUN^. 301 



occurs at Epping and in the London district, and is the form taken at 

 Cambridge, but, as yet, we cannot say whether it prevails throughout 

 the counties eastwards of this line." " Callnnae prevails universally 

 north of Manchester, also westwards from Hampshire to Cornwall ; 

 but we have no certain information yet about Wales" [K.M.M., iv., 

 p. 15). Bond says : — " I have this season, pupa; from Staffordshire, 

 which have been lying by all the winter. The imagos are now 

 appearing, and of six individuals which have already emerged, one of 

 them is certainly the form called (jwn-us, and differs in no respect 

 from those that only passed about a month as pupse bred some seasons 

 ago, from Cambridgeshire" (E.M.M., iv., p. 36). Bond further says 

 that he can " assert that quercils does occur in Ireland, for, some years 

 ago, I captured three specimens near Queenstown, and saw many 

 more on the Aving, and I still have an example in my cabinet." 

 Porritt also shows {E.M.M., vi., p. 191) that Hellins' notion of the 

 distribution of the two insects was more or less incorrect, for he 

 records the larvte of JL quercm as common on the sandhills at Lytham 

 on May 17th and 18th, 1869. Again, in 1870, Porritt writes {K.M.M., 

 vii., p. 17) that on April 15th, at Southport, he found the larv^ of 

 B. (jueniis common, more especially on the south sandhills. 



(6) Captain Thompson thinks that the wing rays and the shape of 

 the curvature of the bands are of " great use in enabling the student to 

 distinguish the races at once." In a general way, I quite agree with 

 this, although neither character will bear any close examination. 

 Hellins says f E.M.M., iv., p. 15) : — " I suppose it is generally known 

 that the distinction between qiierciU and callunac really lies in the 

 different curves of the pale fascia on the wings of the moths, and not 

 so much on the greater or less depth of colour, nor on the length of 

 time passed in the pupa state." 



I think that I have now drawn attention to the leading points 

 that have made lepidopterists generally accept, or, at least, silently 

 acquiesce in, the general principle laid down by Bond, who (J'^.M.M., 

 iv., p. 36), "after some years' attention to the subject," was " inclined 

 to believe that quercus and callunae are only forms of one variable 

 species." 



One of the most important scientific facts relating to these insects 

 was quite overlooked by Captain Thompson. This was Mr. Merri- 

 field's temperature experiments f Trans. Ent. Soc. Loud., 1892, pp. 39- 

 40), and the conclusions that he deduced from them. The pupa; of 

 B. qiu'fcas, which were experimented upon, came from Windsor, those 

 of B. callunae from Perth and Aberdeen. He found that " the same 

 general result obtained in both forms, that is, those at the higher 

 temperature were lighter than those at the lower temperature. This 

 particularly applies to the males, the females varying less, but in both 

 males and females, the forced ones have a reddish tint, Avhich is 

 wanting in the others. In some cases the effect of temperature is so 

 considerable that I think some of the forced callunae would, so far as 

 regards colouring, be classed as quercus, while the individual quercus, 

 brought out in 71 days at the lower temperature, is very dark for 

 (juercns. I think these experiments tend to shoAv that the southern 

 form and its northern car. are respectively varieties of so fixed a kind 

 when they reach the pupal stage, that it is probably only in exceptional 

 instances, if at all, that temperature could convert the one form so 

 far as its appearance is concerned, into the other." 



