habits of certain species of Eiirytomides. 315 



14. E. microneura. From a Cecidomyia upon " Weiden- 

 rosen-zucht." 



15. E. hriinnii'entris. From an oak-gall. 

 With the addition of — 



16. E. lilumata, 111. From the Microgaster of a 

 Liparis. 



The group of Eurytomides, and especially the real 

 economy of Eurytoma hordei, engaged the attention of 

 the late Benjamin D. Walsh, M.A., and formed the suh- 

 ject of two elaborate memoirs published in the ' American 

 Entomologist,' vol. i., pp. 149 — 159 (1869), and vol. ii., 

 pp. 297, 329, and 367 (1870). 



The first of these memoirs is especially devoted to the 

 joint worm {Isosoma hordei), the larva of which is de- 

 scribed as but little more than one- eighth of an inch 

 long, and of a pale yellow colour, with the exception of 

 the jaws, which are dark brown. It inhabits a little cell, 

 which is situated in the internal substance of the stem 

 of the affected plant of wheat, barley, or rye, usually a 

 short distance above the first or second knot from the 

 root, the outer surface of the stem being elevated in a 

 corresponding elongate blister-like swelling ; and when, 

 as is generally the case, from three to ten of these cells 

 lie close together in the same spot, the whole forms a 

 woody enlargment honeycombed by cells, and is in reality 

 a many-celled or " polythalamous " gall. Occasionally, 

 but rarely, galls are situated in the middle of the inter- 

 node, or even close to the upper knot. The mischief 

 done by these insects is in certain localities "seriously 

 great." In 1861, throughout a large portion of Virginia, 

 "many crops of wheat were hardly worth cutting on 

 account of their attacks." In central New York Mr. G. 

 Geddes, late President of the New York State Agri- 

 cultural Society, writes : — "Formerly we expected forty 

 bushels of barley to the acre ; now we cannot rely on 

 more than twenty."— (' Trans. N. Y. Agr. Soc.,' 1859, 

 p. 332). 



The fact of the deposition of the eggs by the female 

 E. hordei in the healthy stalks of the plants was dis- 

 tinctly observed and described by Mr. Pettit, of Grimsby, 

 Canada West ('Canada Farmer,' 1867, p. 268). He 

 states that he had "watched the growing barley, and on 

 the 10th of June found the perfect insects actively at 

 work ovipositing in tJoe then healthy stalks of the plant." 

 After leisurely creeping up and down the plant, "the 



