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XIX. Notes on Chalcididse ; and Description of a new 

 species o/^ Megastigmus. By F. Walker, F.L.S. 



[Read 7th June, 1869.] 



A PEW species of Megastigntus inhabit England. M. 

 giganteus, the largest species of the genus hitherto 

 described, is a native of S. Europe. M. Pistacice, so 

 named by Haliday, and presented by him to the British 

 Museum, is a very elegant Italian species. The known 

 Australian species are smaller than most of those of 

 Europe. M. Pinus of Parfitt, and the species here de- 

 scribed, are natives of California, and are both of large 

 size. There is an affinity in structure, colour, and mark- 

 ings between some species of this genus and some of 

 Decatoma. The latter genus is one of the Eurytomidce, 

 and, like Megastigmus and Eurytoma, is parasitic, on gall- 

 making insects. A North-American species of the 

 Eurytomidce was described many years ago as Eurytoma 

 hordei. Harris, the original describer. Fitch, and Walsh, 

 at first supposed it to be parasitic, but were afterwards 

 convinced that the larva is herbivorous. Walsh has 

 recently observed that it is not a Eurytoma, but an Iso- 

 soma, and that it is very injurious to the corn in the 

 Eastern States from Virginia to Canada. He supposes 

 that all the species of Isosoma are herbivorous, and that 

 Eurytoma hordei, Harris ; E. tritici, Fitch ; E. secalis, 

 Fitch; and E.fulvipes, Fitch, are one species. I have 

 reared several species of Eurytoma from various kinds of 

 galls, but never had an opportunity of observing the 

 transformation of Isosoma. The British species of the 

 latter genus are numerous, and various in structure, and 

 some of them are yet undescribed. Giraud reared in 

 Austria three species of Isosoma and Pimpla graminellcp., 

 Grav., from Triticum repens, and believed them to be all 

 parasitic on a Dipterous insect. If these species of Iso- 

 soma are herbivorous, it would seem that Pimpla grami- 

 nellce, an ichneumon-fly, which much exceeds them in 

 size, and is very abundant in England, is their parasite. 

 Walsh observes that one of the Pteromalidce, which he 

 names Semiotellus chalcidiphagus , is parasitic on Isosoma 

 Jiordei. He also describes Antigaster mirabilis, a new 

 genus, allied to Eiipehnus and to Notanisus. Chiropa- 

 chys colon, of vfhich the natural history was lately noticed 



TRANS. ENT. SOC. 1869. — PART IV. (aUGUST) . 



