G17 



puparia of Chortophila brassicae (cabbage-root fly) : — Ichneumons, 

 Atractodes tenebricosus, Grav., and Phi/gadeuon fumator, Grav ; 

 Cynipid, Cothonaspis {Eucoila) rapae, Westw. Puparia of C. brassicae 

 were collected from market-gardens and allotments in the vicinity of 

 Northenden and Sale, Cheshire, during every month in 1914, except 

 April and May, and in the early months of 1915. Puparia of this fly 

 may be found throughout the year wherever cabbages and related 

 vegetables are grown ; those of the first brood occur in June 

 and July, those of the second in August and September. During 

 the succeeding months, until the following May or June, they are 

 present in the soil. It is uncertain whether these belong to the second 

 or a subsequent generation. Parasitised pupae were detected by 

 examination under a low power microscope ; they were then placed, 

 until required, in boxes containing moistened sterilised sand. No 

 difficulty was experienced in obtaining fertile females, ova, and larvae 

 of the Staphylinid in captivity. Living larvae and the extracted 

 contents of puparia of the cabbage fly were given to the beetles for 

 food. If puparia were placed in the breeding- boxes for the newly- 

 hatched larvae to enter and if proper conditions of moisture and 

 ventilation were maintained, the complete developmental cycle could 

 be observed. Experiments were made with the object of hastening 

 the develoT3ment of the larvae during the winter, by subjecting infested 

 puparia to moist, warm conditions. The temperatures varied from 

 60-5° F. at night to 74-5° F. in the day, during the period 

 from 8th January to 8th February 1915. Adult beetles were obtained 

 in one month from the time the infected puparia were placed in the 

 warm room ; normally, these adults would have emerged in May or 

 June. The ova of A. bilineata are deposited in the soil, near the roots 

 of cabbages, etc., which are attacked by the larvae of C*. brassicae. 

 The larvae hatch in from 10 to 12 days. Their natural habitat is 

 below the surface of the soil. In order to complete development, it 

 is essential for them to enter Dipterous puparia ; whether they are 

 restricted to the puparia of C ■brassicae is at present undetermined. 

 Three small Anthomyiid puparia, apparently distinct from C. brassicae, 

 and containing Staphyhnid larvae, were found during the winter ; 

 a very small adult A. bilineata was reared from these. The time 

 required by the larva in effecting an entrance into the puparium is 

 apparently very considerable. The young larvae probably puncture 

 the pupal cuticle and ingest the semi-fluid contents. In summer from 

 12 to 18 days elapse from the completion of feeding to the last larval 

 ecdysis and appearance of the pupa. The pupal stage lasts about the 

 same time. In captivity, adults attacked larvae and occasionally 

 pupae of C. brassicae. From infected puparia collected at the end of 

 March 1914, the first adult beetle emerged on 20th May, the last on 

 23rd June. Under out-door conditions emergence would probably 

 have been later. Cabbage-fly puparia resulting from the first brood 

 of flies, were collected at the end of June and early in July ; some of 

 these contained first stage Staphylinid larvae. Judging from the 

 results obtained by subjecting larvae to warm conditions, and also 

 from the time occupied for the development of the summer brood, 

 it seems probable that three or more generations might be produced 

 under warm climatic conditions, though, in the vicinity of Manchester, 

 there is no evidence to show that three generations normally 



