Gall- Dwellers. xiii 



is always necessary to see that the gall-maker, and not 

 a Synergus, has been obtained \ Both Malpighi and 

 Canon Derham were aware of the attacks of parasites, 

 and actually saw galls pierced by them. The latter says, 

 ' I apprehend we see many vermicules, towards the 

 outside of many oak-apples, which I guess were not 

 what the primitive insects laid up in the gem from which 

 the oak-apple had its rise, but from some supervenient 

 additional insects, laid in after the apple was grown, and 

 whilst it was tender and soft-.' Ratzeburg, a forester 

 like Hartig, in his beautiful ' Forstinsekten ' ^ corro- 

 borated Hartig's division of gall-dwellers. Giraud, 

 Schenck, Reinhard, Taschenberg, Schlechtendal, 

 Wachtl, Forster, and Lichtenstein, have since each 

 advanced our knowledge of the Cynipidae, and the 

 history of galls generally has been admirably written by 

 Lacaze-Duthiers. The entomologists of America have 

 not been behind those of Europe ; Baron C. R. Osten- 

 Sacken, before he quitted America in 1877, had discovered 

 eighteen new species ; Bassett, thirty species, and Walsh 

 and Riley had each added much to our knowledge. 

 Professor Gustav Mayr of Vienna has not only increased 

 largely the work of previous observers, but has 

 arranged all that is known of gall-makers and gall- 

 dwellers in a series of admirable monographs * and has 



^ See Walker, Ent. Mag. vii. p. 54. 



^ Derham, Physico-theology, iii. p. 389. 



^ Ratzeburg, Die Foysiinsektett, vol. iii, Berlin, 1844. 



* Mayr, G., Die niitteleuropdischen Eicliengallen in lVo}i itnd Bildetn^ 

 Wien, 1870-71 ; Die Einmiethler der niitteleuropdischen Eichengallen, 

 Wien, 1872; Die eiiropdischen Cynipiden- G alien mit AusscMhss der auf 

 Eichen vorkotnnienden Arten, Wien, 1876; Die europdischen Torymiden, 

 Wien, 1874; Encyrtiden, 1876; Olinx, 1877; Eurytoma, 1878; 

 Telenonitis, 1879; Die Genera der gallenbewohnenden Cynipiden, V^\en, 

 1881 ; Die europdischen Arten der gallenbewohnenden Cynipiden, Wien, 

 1882. 



