FAMILY HABITS IN BUTTERFLY LARVvE THE COLIADS, ETC. 55 



CHAPTER IX. 



FAMILY HABITS IN BUTTERFLY LARViE THE COLIADS AND 



GONEPTERYGIDS. 



The "clouded yellows" and "brimstones" have many structural 

 features in common, in all their stages — egg, larva, pupa, and 

 imago — yet the general habits of their larvae are widely different 

 in most of the broad features presented. The larval habits of the 

 Coliads are, in one character at least, also widely different from those 

 of the Pierids, Pontiids, Anthocarids and Gonepterygids, viz., the 

 Coliads have winter-feeding larvae. Like the true Pierids, they 

 produce "forwards" very freely under suitable climatic conditions in 

 the lower latitudes and altitudes that they inhabit, and the peculiar 

 characteristics exhibited in this direction, often resulting in continuous- 

 broodedness both in the Nearctic and Palaearctic regions, are somewhat 

 remarkable, yet, in the most marked polygoneutic forms, the larval is 

 the stage in which the insects pass the winter. In stating that the 

 larvae have winter-feeding larvae, it must be understood that this is 

 the family habit, exhibited by all species, whether single-, double-, or 

 many-brooded. In those with more than one brood, the species have 

 of course summer-feeding larvae in addition, so that these may be said 

 to differ from the true Pierid larvae in having not only spring-, and 

 summer-, but also winter- (autumn-to-spring-) feeding larvae. 



The "forward" habit is, in this group, specially worthy of attention. 

 The species of quite high latitudes and high altitudes, e.g., Colias 

 jphicomone, C. palaeno, Colias meadii, C. interior, etc., are dis- 

 tinctly single-brooded ; in other species (Colias hyale, C. myrmidone) 

 limited to moderately temperate climes, a double-brooded habit is 

 engendered, the larvae hybernating from September or October until 

 mid-March, whilst, in others (Colias edusa, C. eurytheme, etc.), with 

 their real home in warm temperate and even subtropical areas, a 

 many-brooded habit is the rule, a partial hybernation occurring from 

 November to February. The fixity of this many-brooded habit is 

 apparently the real cause of the repeated annihilation of these species 

 in the cooler temperate regions to which their wandering habits lead 

 them, the larval habits not including a sufficiently prolonged hyber- 

 nating period to enable them to live through a long winter. On the 

 other hand, it is generally supposed that the larvae of the subarctic 

 species have a habit enabling them to hybernate over at least two 

 winters if necessity arises. We have no information as to whether 

 Colias palaeuo or C. phicovwne ever develop "forwards," but Edwards 

 notes (Can. Ent., xxi., p. 42) that, of a batch of larvae of C. meadii, 

 hatched July 23rd, 188S, one larva alone fed on pupating August 19th, 

 and producing an imago on August 25th, whilst all the other larvae of the 

 brood fed up slowly till after the third moult, commenced to hybernate 

 on August 28th, and did not produce imagines till the following year. 

 The two common American species appear to have almost exactly 

 parallel habits in this respect with our two common European species, 

 viz., Colias jihilodice with C. hyale, and C. eurytheme with C. edusa. 

 The former are double-brooded in the northern parts of their range, 



