43 



Larval Stages of Chrysopora hermannella, Fab. 



By Alfred Sich, F.E.S. Read Dece?nber 9///, 1909. 



This small but very beautiful moth may be occasionally seen on 

 sunny mornings, flitting about plants of Chenopodium, in May and 

 June, and again in August. Its colours are black, orange, and silver. 

 It may be known from all our other British black and red moths by 

 the shape of the hind wing, the hind margin of which is sinuate and 

 the apex elongate. It looks as though a piece had been bitten out 

 of the hind margin. 



The larva mines between the cuticles of the leaves of the common 

 goose ioot {Chenopodiin>i), and is somewhat remarkable for the colour 

 changes that it undergoes during its larval existence. In 1908 the 

 larva was very abundant in Chiswick, and I therefore took the oppor- 

 tunity of making a few notes, a summary of which I have the 

 pleasure of bringing before you to-night. 



The larva quits the egg by boring through the shell into the leaf, 

 and if the egg has been laid on the lower surface of the leaf, as is 

 generally the case, the larva makes a spiral mine through the thick- 

 nt ss of I he leaf in order to reach the upper surface, because through- 

 out the feeding period the larva always mines just below the upper 

 cuticle of the leaf. Also, it always mines venter uppermost and is 

 essentially a gallery miner, though in the last stadium the wide 

 gallery is turned often so closely on itself that the mine has some- 

 what the appearance of a blotch mine. The mining life of the 

 caterpillar is divided into four distinct stages, and each stage has its 

 own particular mine. The first part of the mine, corresponding to 

 the first stadium of the larva, is a very slender gallery, only o"i5 mm. 

 wide, and it runs with several turns to a length of from 7-10 mm. 

 It has the appearance of a very fine black thread. If we examine 

 the end of the mine we shall see that the last millimetre has a dark 

 pink line running down the centre of the mine. This is the ventral 

 stripe of the larva showing through the cuticle of the leat. This 

 portion of the mine takes the young larva about three days to com- 

 plete. The larva now slightly widens the mine and then lies up for 

 the first change of skin, which takes place some twenty-four hours 

 later. The full-fed larva in the first instar measures just about 

 I mm. in length. As in many young miners, the thorax is rather 

 swollen. The body is very shining pale grey on the back, but 

 beneath, it is yellowish with a broad orange band running nearly the 

 whole length of the larva. It has three pairs of thoracic legs, which 

 are broad and strong. After the change of skin the larva continues 



