PARASITES. 11 



larva. Chapman (Ent. M. M., ix, 13) records a Chalcid 

 feeding on the imago of Biorhiza aptera. The eggs 

 are not always laid in the body of the victim. 



The third class — the commensals — are mostly 

 found in the large galls, such as those of Andricus ter- 

 minalis, and feed on the gall mass without, as a rule, 

 interfering with the development of the host. Cetonia, 

 Balaninus, and various moths devour the tissue. 

 As an example of the manner in which the terminalis 

 galls afford lodging and food to insects, it may be here 

 recorded that the late Francis Walker (Zool., 1846, 

 p. 1454) reared the following from amass of terminalis 

 galls ; namely, Goleoptera, 9 species, 191 specimens ; 

 Orthoptera, 1 species, 5 specimens ; Neuroptera 

 (Psocus), 2 species, hundreds of examples ; Gynipidse, 

 4 or 5 species, 30,246 specimens ; parasitic Hymen- 

 optera, 45 species, 24,417 specimens ; Diptera, 3 

 species, 23 specimens ; Lepidoptera, 5 species, 9 

 examples ; Hemiptera, 5 species, 51 specimens ; 

 Arachnidm and Acari, 5 or 6 specimens. Total, 75 

 species, 55,000 specimens and upwards. 



The chief works, from the biological point of view, 

 on the parasites of gall-flies are — 



Batzeburg. Forstinsecten. 



Mayr. Die Europaischen Torymiden (Yer. z.-b. 

 Ges. Wien, xxiv, 1874; Die Ohalcidier-Gattung Olinx 

 (1. c.j xxvii) ; Die Arten Ohalcidier-Gattung Eury- 

 toma (1. c.j xxviii). 



Giraud. Liste des eclosions d'Insectes observees 

 par le Dr. Joseph Etienne Giraud, recueillie et 

 annotee par M. le Dr. Alexander Laboulbene (Ann. 

 Soc Ent. Fr., 1877, 397). 



Kirchier. Catalogus Hymenopterorum Europse. 



Kaltenbach. Die Pflanzen-feinde. 



The purely descriptive works are those of — 



Walher. In the Entomological Magazine and in 

 his Monograph ia Chalciditum (1839). 



Holiday. In the Entomological Magazine, 



