COCOON COLOUR OF VARIOUS INSECTS. 153 



of the abdomen is shorter than 3 (counting the first body segment 

 as 2) 2 striate at proximal half (in the genotype striate for proximal 

 three fourths), 3 striate at base (for nearly the entire segment in the 

 genotype, though but faintly after middle) ; segment 4 shorter than 3 

 (longer in the genotype, sub-equal to 2). The whole of the venation 

 from base to the apex of the elongate postmarginal vein bears 

 conspicuous, long, stiff bristles (in the genotype less conspicuous, 

 the postmarginal vein otherwise indistinct but for them). Marginal 

 vein nearly as long as the stigmal vein, thrice longer than wide (in 

 the genotype hardly twice longer than wide, less than half the length 

 of the longer stigmal) ; otherwise the same. Mandibles with three 

 small acute teeth at apex. 



Three females. 



Types. — Catalogue No. 20601, U.S. National Museum, the 

 females on a slide. 



The original description of the genus needs emendation as 

 follows : 



Antennae in female 11-jointed, the club 4-jointed ; lateral ocelli 

 distant from the eyes ; scrobes very deep but short, separated by a 

 thin carina ; eyes hairy ; propodeum with a curved lateral carina ; the 

 postmarginal vein is present, elongate, over twice the length of the 

 stigmal ; the latter very narrow, its knob small and abrupt. Mandibles 

 tridentate, the middle tooth shortest, the others subequal. Abdomen 

 depressed from dorsal aspect, ovate, the base truncate and margined, 

 none of the segments very long, the abdomen a little longer than the 

 rest of the body. Habitus of Telenomus. Meson of propodeum 

 declivous and against the abdomen (but when visible striate as in 

 hrittanica, but not out to the spiracles). Male antennse 12-jointed, 

 moniliform, except the club and funicle 1, the former longer than the 

 latter, longer than the pedicel (which is not so elongate in the male)." 

 From types of the genotype. 



ON THE COCOON COLOUR OF VARIOUS INSECTS. 

 By G. T. Lyle, F.E.S. 



Until I read Mrs. Merritt-Hawke's paper, " On the Factors 

 which determine the Cocoon Colour of Plusia moneta and other 

 Lepidoptera," published in the 'Trans. Entom. Soc, 1916, p. 404, 

 I was under the impression that for some time past it had been 

 an accepted fact that the variation in colour of the cocoons 

 of P. moneta is due entirely to the absence or presence of 

 moisture. 



Some years ago I reared a considerable number of the larvae 

 of this species with the idea of obtaining hymenopterous para- 

 sites, and my experience abundantly proved that, given a total 

 absence of moisture, the cocoons were invariably white, while, 



