4 ENTOMOLOGICAL NEWS. [January, 



Note on the Larva of Pachylia ficus (L.) 



By T. D. A. COCKERELL, Kingston, Jamaica. 



Pachylia ficus (Linn.) Length about So mm. Head shiny jet-black, 

 except the mouth parts, which are pale greenish. Thoracic shield dull 

 black; the short caudal horn and the anal plates are black. Spiracles 

 blackish. Body: back dull red, sides and under part dull pale bluish 

 green, the two colors sharply denned; with a pale red longitudinal line 

 near the lower edge of the red color on each side. On each of the last 

 eight segments is an obscure narrow whitish oblique line on the green 

 sides, crossing the spiracles. Legs pale bluish green, like the underside; 

 sides of body wrinkled. 



Food-plant, Ficus sp. 



Described from a mature specimen about to pupate, found in 

 Kingston, July 21, 1891. The moth emerged August i3th. 

 Another mature larva, also found in Kingston, was brought to 

 me by Anna Ashburn on the 2d of September. 



The larva of this species is glaucous-green, whitish above, with 

 a narrow yellow stripe on each side; until shortly before it changes 

 to a pupa, when it assumes the very different coloration described 

 above. This change of color is almost certainly protective, the 

 red back being less conspicuous than whitish or green, as the 

 larva crawls about in search of a suitable spot to pupate in. 



In Weismann's "Studies in the Theory of Descent," p. 232, 

 there is a foot-note by Prof. Meldola, in which this change is de- 

 scribed from Burmeister. This account does not quite agree with 

 the Jamaica larva, and if in South America the larva really changes 

 after the third stage, and lives on the tree and feeds after assum- 

 ing the red coloration, it apparently affords an instance in which 

 a phase of color has arisen as protective at larval maturity, and 

 has become so strong in the organization of the insect as to ap- 

 pear in some districts earlier in the life of the larva than is actually 

 of use. It would be a curious case if it could be shown that this 

 character had first appeared as useful, and had at length become 

 injurious by reason of its excessive development! However, it 

 is not so in Jamaica, and if the account of Burmeister' s larva is 

 correct, it may still be that there are some special conditions of 

 environment in the district where it was found, that render the 

 red useful not only at pupating time, but also on the tree. This 

 might be the case, for example, if it fed on a tree whose leaves 

 turned red at a certain time. 



