66 



BRITISH BUTTERFLIES. 



soft tissue of the leaf as far as it can reach, and even doing some 

 burrowing when in its third stadium. Chapman observes that, 

 when about halfgrown, the larva? of this species and Nordmannia ilicis, 

 one of the Strymonids, have a habit of hiding by burying themselves 

 on the upperside of an oak-leaf, along the midrib, the petiole being 

 too short to count, with the head pushed as far as may be into the 

 axil. In this position they are remarkably invisible, the oak at this 

 stage having both green and red- brown tints to which these larvae closely 

 assimilate, the larva of N. ilicis chiefly green, that of B. quercus brown. 

 The larva of Ruralis betulae hides and burrows less than that of B. 

 quercits. From the first, it will eat through the whole thickness of a 

 young leaf of plum or blackthorn, and practically does no boring as do 

 its allies, and from its second instar until fullgrown its feeding-habits 

 and resting-habits are practically identical. It nearly always rests 

 under a leaf, and usually selects an uneaten one on which to rest, and 

 Chapman observes that the difficulty of finding a larva of this species 

 of over -5in. long, on a little bit of sloe with 20 or 30 leaves, is quite 

 ridiculous. In looking for it, one sees its dorsal ridge in profile, it 

 proves to be a margin of a leaf; one sees its " slope," it is the light 

 shining through a curled portion of a young leaf ; one sees it half-a- 

 dozen times in this deceptive fashion before actually spotting it. Then 

 one wonders how one could have missed it so long, it is so obvious, 

 and, taken altogether, not at all like a sloe-leaf ; yet any view of the 

 group of sloe-leaves gives several items that are very like portions of 

 the larva. The Ruralid larvae, as exemplified by these two species, 

 are distinctly slower-feeding than those of the Strymonids. 



CHAPTEE XL 



FAMILY HABITS OF BUTTERFLY LARV.E THE LYC^NIDS. 



The larval habits of our " blue " butterflies are at the present time 

 so little known that it is almost impossible to write any useful notes 

 thereon. The caterpillars of whole groups of the tropical species 

 remain almost absolutely undiscovered, and, in the few isolated cases 

 in which they are known, practically nothing has been recorded of 

 their habits. 



The Plebeiids are possibly the most generalised in their larval 

 habits, feeding usually on low, leguminous plants, hybernating in the 

 third stadium, eating out, when young, little patches of the cellular tissue 

 from the undersides (or uppersides) of the leaves, and often producing 

 " forwards." Yet there are many exceptions to all these features, e.<j., the 

 larva? of Aricia astrarcke and Polyommatus donzelii feed on Geraniaceae, 

 the latter species and Agriades corydon hybernate as eggs, i.e., as fully- 

 formed larvae inside the eggshell, and many of the species, especially 

 those confined to high latitudes and high altitudes, produce no 

 "forwards" and are entirely single-brooded. 



The structure of the " blue " larva, its small head and long, thin 



