INSECTS 



emerge to form a cocoon or remain in the pupa-case of their victim to await their final transforma- 

 tion. In the case of the larger ichneumons only a single egg is deposited in each larva attacked, 

 but with the smaller forms the number may be considerable. Bignell, for instance, has hatched 

 1 80 braconids out of a single larva of Arctia ca/a, and I2OO Microgaster have been bred out of 

 another Lepidopterous caterpillar. 



Though a few ichneumons are apparently limited to a single host, the majority have a fairly 

 extended choice. Morley mentions that the common Cryptid, Hemiteles areator, has been bred 

 from eighteen different Lepidoptera, including Bombyces, Tortrices, and Tinea ! 



Lepidoptera are the best known, but by no means the only victims. Many of the 

 Tryphoninae are parasitic on saw-fly larvae, though the Schizodontes for the most part affect 

 Diptera. The Pimplinae prey largely on the larvae of Coleoptera and Aculeate Hymenoptera, 

 and several of the species attack spiders. An entire section of the Braconids, the Aphidiidae, devote 

 themselves exclusively to Aphides, and a large number of still smaller forms finds sufficient material 

 for the growth and development of one or more individuals inside the egg of another insect. 



Just as there are insects that prey upon insects, so there are parasites that prey on parasites. 

 These hyperparasites are very numerous, and act as an effective check on the too rapid increase of 

 the parasitic ichneumons and the consequent excessive destruction of lepidopterous and other 

 phytophagous larvae. In such species the parent insect lays her egg in the body of a parasitic 

 larva already ensconced within a vegetable-feeding caterpillar, and this egg develops and attains 

 maturity at the ultimate expense of the two enclosing hosts. The extensive Ophionid genus 

 Mesochorus is entirely composed of hyperparasites, and they are well represented in many other 

 groups. 



Ichneumons as a rule are extraordinarily agile in their movements and swift and sudden in 

 their flight. During the summer they are abundant almost everywhere throughout the county, 

 and are often taken in considerable numbers at expanding foliage in spring. Many species are fond 

 of plant honey, and may be taken in quantity at nectar-producing flowers. -As in the case of 

 the saw-flies, umbelliferae generally possess a powerful attraction for ichneumons, and clumps of 

 angelica, hogweed, and rough chervil are excellent collecting stations when the weather is 

 bright. 



The only published list of Cornish Entomophaga is one of 125 species by Mr. E. D. Marquand 

 in a paper ' The Ichneumonidae of the Land's End District ' in vol. i (new series) of the 

 Transactions of the Penzance Natural History and Antiquarian Society (1880 4). In his 'Fauna of 

 Plymouth; Ichneumonidae,' in the Transactions of the Plymouth Institute, 1 88 1 6, Mr. G. C. Bignell 

 includes some Cornish captures, and there are many references to records from the county in 

 Mr. C. E. Morley's recently-published British Ichneumons. 



Most of the species on the accompanying list have been taken, and a few bred by the students 

 at the County Technical Schools, Truro, where on account of its supreme importance to agriculture 

 and horticulture the sub-order is being made a subject of special study. The diffuse character of 

 the literature on British Ichneumons and their allies has made the work of identification very 

 difficult, and the fragmentary character of many parts of the accompanying list is due far more 

 to this cause than to the lack of material. Several of the sections have not so far been studied at 

 all. As no dubious species has been allowed on the list these sections are not represented. 



The writer wishes to acknowledge his indebtedness to Mr. G. C. Bignell for genial assistance 

 so kindly given, and also to the late Rev. T. A. Marshall of Botus-Fleming, by whom it had been 

 fondly hoped this article would have been written. 



ICHNEUMONIDAE 



LISTRODROMIDES JOPPIDES (continued) ICHNEUMONIDES 



Listrodromus, Wesm. Protichneumon fuscipennis, Wesm. OXYPYGINI 



nycthemerus, Grav. disparis, Poda. 



laminatorius, Fab. Stenichneumon, Thorns. 

 TOPPIDFS Coelichneumon, Thorns. culpator, Schr. 



sugillatorius, Linn. pistorius, Grav. 

 Hoplismenus, Grav. fuscipes, Gmel. trilineatus, Gmel. 



perniciosus, Grav. periscelis, Wesm. ochropis, Gmel. 

 Automalus, Wesm. leucocerus, Grav. Cratichneumon, Thorns. 



alboguttatus, Grav. comitator, Linn. sicarius, Grav. 

 Trogus, Panz. bilineatus, Grav. rufifrons, Grav. 



lutorius, Fab. consimilis, Wesm. nigritarius, Grav. 



exaltatorius, Panz. lineator, Fab. fabricator, Fab. 

 Protichneumon, Thorns. ruficauda, Wesm. annulator, Fab. 



fusorius, Linn. castaneiventris, Grav. fugitivus, Grav. 



I 177 23 



