Insects. 



7889 



Immediately after each moult the heads of my larvae were yellowish 

 white and the thoracic legs pale green ; this colouring remained but 

 a very short time. Not long after the moult the former became brown, 

 and the latter assumed the usual darker tint. 



My first larvae were full-grown by the end of July. They then spun 

 cylindrical cocoons among the withered leaves lying at the bottom of 

 the glass vessel in which I kept them. These cocoons were from 4 to 

 5 lines or 10 to 12 mm. in length ; they were rounded at either end. 

 They may be known by the strength and pergamentaceous nature of 

 their walls; the colour is, however, very variable, for those individuals 

 which spin in and under the moss at the foot of the pine trees gene- 

 rally form brown, sometimes even dark brown, cocoons, while those 

 which spin up in the angles of the twigs usually make silky ashy 

 gray, white or yellowish white cocoons. (See fig. 3). 



In the case of a very nearly allied species, Lophyrus similis, I once 

 observed that all those which had spun up on the twigs were attacked 

 by parasitical wasps, while those cocoons which had been formed at 

 the foot of the tree produced perfect sawfiies. I cannot possibly say 

 whether this was merely a chance observation or whether it was in 

 any wise an illustration of a rule, but I can confidently assert that 

 no such rule or, if one may say so, law of disease is observable in the 

 case of Lophyrus Pini. Hartig remarks that the spring brood, which 

 appears in July, spins up among the branches, whilst the remainder 

 hide in the moss ; but, as in the case of those I observed, out of one 

 and the same brood one individual became an imago after being one 

 month in the pupa state, whilst the others remained over for eleven 

 months, I find some difficulty in accepting his statement without fur- 

 ther observation. Those cocoons which have been opened by the 

 sawfly itself may be known by their having a little lid, as it were, cut 

 out as if by a sharp instrument, as shown at fig. 3, whilst those cocoons 

 which have produced parasitic wasps have a small oval or round hole 

 at the side, and on the other hand those which have been infested by 

 parasitic Diptera have an irregular opening at one end. 



Inside of this pergamentaceous cocoon the larva passes sooner or 



spot on the clypeus; there was also a black circle immediately round the eyes. Abdo- 

 men dull green, greenish yellow underneath ; a very irregular black stripe extended 

 over the back. On a level with the stigmata was a row of eleven Mack spots; similar 

 marks were observable above the anterior legs; over the prolegs was a pitchy black 

 spot preceded by a Mack dot; the terminal segment was smooth, without wrinkles. 

 From these larvas were reared one male and three female images." 



VOL. XX. K 



