114 GENUS TRIGONASPIS. 



The inquilines are Synergus pallicomis, melanopus, 

 and Beinhardi, all of which have been reared from 

 them here. Kaltenbach (Pfl., 668) gives 8. facialis 

 also as an inqniline, and, as indicated on p. 58, Billups 

 records the rearing of Geroptres arator from the galls, 

 but it is quite possible that the specimens were reared 

 from the twig galls of Andricus noduli. 



The empty galls are much utilised by various out- 

 living insects for purposes of pupation. Fitch (Ent., 

 1879, p. 113) gives a list of the insects and their 

 parasites raised by Mr. Weston from a lot of the galls. 

 These included six species of Lepidoptera, seven 

 beetles, and thirty Hymenoptera. The latter included 

 Dineura Degeeri (a birch-feeding species), Emphytus 

 togatus, and Harpiphorus lepidus ; nine species of 

 Ichneumonidse, one Braconid, Eurytoma rosx, Synto- 

 maspis caudata, Torymus regius, Megastigmus stigma- 

 ticans (the latter no doubt parasitic on the gall larvae), 

 a Lamprotatus, Pteromalus tibialis (also a gall larva 

 parasite), two species of Homalus (H. auratus and H. 

 cwmleus), two Crabronidse, Odynerus trifascatus, and 

 the bee, Prosopis rupestris. 



The flies emerge in August or September. 



Distribution : Germany, Austria. 



Genus Tbigonaspis. 



Trigonaspis, Hartig, Germs. Zeit., ii, 186 ; Mayr, Genera, 30. 

 Biorhiza, Westwood, Int., ii, 56 (part). 



Agamic. — Apterous ; parapsidal furrows incomplete ; antennae 13 to 14 

 jointed ; no keel between the antennas ; head not dilated behind ; ventral 

 thorn 2 to 2| times as long as thick. The third joint of the antennae 

 twice as long as the fourth, the sixth to twelfth not longer, as thick. 

 Scutellum separated from the mesonotum by a slight transverse 

 furrow. 



Sexual. — Antennas 14-jointed $ , 15-jointed $ ; flagellum rather 

 slender, tapering towards the apex. Parapsidal furrows complete, 

 distinct. Scutellar foveas shallow, separated by a sharp furrow ; the 

 keel in front of them distinct, acute. Scutellum rugose. Median seg- 

 ment with the keels parallel. Abdomen shorter than the head and 



