AULAX SOABIOSJE. 51 



regards size. They are hard, usually coloured like 

 the stem, but with age get paler, and contain 

 numerous larval cells of the usual form irregularly 

 distributed through the mass. In size I have found 

 them from a quarter to over an inch and a half in 

 length. The outer surface is more or less thickly 

 haired, but old examples are usually glabrous. 



On Triticum the larvas live in the roots, which they 

 do not distort very much. Several live in cells 

 together, as in Hieracium. 



The parasites are Torymus hieracii, Mayr ; T. chlo- 

 rinus, Foer. ; T. euchloris, Bohm. ; T. rubi, Schr. ; 

 Eurytoma signata, Nees ; E. flavo-scapularis, Ratz. ; 

 Decatoma hieracii, Gir. ; Systole castaniventris, Grir. ; 

 Tetrastichus quercus, Walker ; Pteromalus aurantiacus, 

 Ratz. ; Tetrastichus Andrewii, Ratz.; T. planiusculus, 

 Foerster. 



The species is of wide distribution in Britain and 

 in Europe. 



5. AULAX SOABIOS^]. 



PL XI, fig. 2, gall. 



Diastrophus scdbiosse, Giraud, Verh. z.-b. Ges. Wien, 1859, 368. 

 Isocolus scabiosse, Foerster, 1. c, 1869, 334. 

 Aulax scabiosse, Mayr, Eur. Cyn., 10 ; Oyn. Gallen, 11, fig. 6. 

 Aulax centaurese, Thorns., Opusc. Ent., 809, 19. 



Black ; the knees, tibiae, and tarsi ferruginous ; wings hyaline ; the 

 nervures reddish ; the areolet absent ; the fore wings not ciliated. 

 Head and thorax opaque, transversely rugose; the face and pleurse 

 aciculated. Scutellum coarsely rugose, without a longitudinal furrow. 

 Abdomen shining ; the second abdominal segment at the apex and 

 the following distinctly punctured. Antennae blackish ; the third and 

 fourth joints subequal. Median segment and collar covered with 

 greyish pubescence. 



Length 3 mm. $ . 



The gall is found as large, strumous, spindle- 

 shaped swellings on the stems of Centaurea scabiosa. 

 These may be as long as two or three inches, and 

 contain numerous cells scattered irregularly through 

 the medullary tissue. 



