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XXXII. Note on the Memoir 'printed at Page 249 of the present f^olume. 

 By John Curtis, Esq., F.L.S. 8fc. 8fc. 



Read January 21st, 1845. 



felNCE my Paper upon the economy of the Dielocerus Ellisii was laid before 

 the Linnean Society, some materials have accidentally fallen in my way, which 

 appear to throw light upon the curious habits of that insect. 



Last autumn I had a cocoon of the Emperor moth {Saturnia Pavonia- minor) 

 transmitted to me, infested by a parasite: the cocoon being divided longitu- 

 dinally, instead of the chrysalis, a series of cells (fig. 1.) was discovered, so 

 analogous to those represented in the present volume (Tab. XXXI. fig. 5.), 

 that I think a doubt can no longer exist that the woolly masses there ex- 

 hibited (figs. 3, 4, 5.) are the cocoons of some large South American Bombyx, 

 and that the substance of the caterpillar has been converted into cells by the 

 larvae of the Tenthredinous insect. Although this will set aside the theory of 

 their having manufactured the nest, a still greater anomaly in their economy 

 presents itself, that of a saw-fly being parasitic. 



One side of the cocoon sent to me last autumn was occupied by hexagonal 

 and irregularly-sided cells (fig. 1, b), but on the other they were nearly 

 choked with the wool (fig. 1, c) : from this it may be inferred that it is the 

 fat on which the parasites subsist, leaving uninjured the vessels and secretions 

 which supply the caterpillars of moths with silken materials for their cocoons; 

 and at the same time there is strong evidence that it is this woolly substance, 

 combined with liquid secretions at the command of the parasitic larvae, of 

 which the cells are formed, and that the quantity of woolly material remaining 

 was a surplus unrequired by the larvae. 



The contents of the cocoon and cells have been subjected to the most rigid 

 scrutiny, but I cannot find a vestige of any perfect insect to indicate the genus 

 of this newly-discovered parasite. I detected, however, a dried and broken 



3 s 2 



