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NOTES ON THE LIFE-HISTORY OF CERTAIN SAW 



FLIES (GENUS PERGA), WITH DESCRIPTION 



OF A NEW SPECIES. 



By W. W. Froggatt. 



In the spring of last year I commenced collecting such larvae of 

 saw-flies (Perga) as were obtainable in the neighbourhood of 

 Sydney with the view of investigating their life-history. Not 

 then sufficiently understanding their habits the earliest batches 

 obtained died prematurely. From other broods, however, collected 

 at Botany and at Rose Bay, saw-flies referable to four species were 

 reared ; and these were supplemented by three other species bred 

 from a consignment of larvae sent me from Nundle, N.S.W., by 

 my father. 



Though several species in their natural state confine themselve.s 

 to particular species of Eucalypts, in captivity all my specimens 

 fed freely on the leaves of Eucalyptus corymbosa, one of the 

 commonest Sydney gum-trees. A large jar with about six inches 

 of sand and rotten wood on the bottom serves very well as a 

 breeding-cage ; and in such a jar with its aperture closed the 

 leaves kept fresh for at least two days. Messrs. Bennett and 

 Scott in their account of Perga eucalypti (P.Z.S., 1859, p. 209) 

 state that the larvae live on Gallistenion as well as liucalyj)ttis. 

 So far I have not myself met with them on any plant but Eucalypts, 



The larvae of each brood cluster together during the daytime, 

 but at night they separate to feed. Several times just about day- 

 break I have come upon them while scattered, but they soon 

 hurried back to their social clusters. 



The cocoons of some species are collected into masses, while of 

 others each cocoon is separate and distinct. Their construction is 

 rather remarkable, for at one eud of the cocoon is a second small 



