Kenneth M. Smith 183 



is predaceous upon the pupae of the Onion-Fly, of the Cabbage Root Fly 

 and aUied species. This larva bores its way through the hard shell of the 

 pupal case and feeds upon the pupa inside, it then completes its develop- 

 ment in the case, emerging later on as the adult beetle. Fig. 10 is a 

 photograph of Aleochara bilineata. 



Methods. The Onion-FUes were studied in the field, in the open-air 

 insectary and in the laboratory; for the two latter methods large glass 

 cyhnders were employed. These were placed over onions growing in pots 

 and the tops were covered with fine musHn. This allowed a clear view of 

 the insects confined within. 



Acknowledgments are due to Mrs Tattersall for her kind assistance 

 in preparing the drawings. 



REFERENCES. 



(1) Seveein, H. H. p. and Severin, H. C. (June 1915). Journal of Economic Entomo- 

 logy, vm. No. 3. 



(2) Sanders, J. G. Journal of Economic Entomology, vm. 89. 



(3) Smith, J. B. and Dickenson, E. L. (Feb. 12, 1907), New Jersey Agricultural 

 Experiment Station, Bulletin 200. 



EXPLANATION OF PLATES X AND XI 



PLATE X 



Fig. 1 A. Eggs of Hylemyia antiqua compared with 



Fig. 1 B. Eggs of Chortophila brasaicae. 



Fig. 2. Posterior spiracles. A. Caudal end of onion maggot. B. Caudal end of 



cabbage root maggot. {After Gibson and Treherne.) 

 Fig. 3. Anterior end of onion maggot, showing spiracle and chitinous ' jaws.' 

 Fig. 4. Full grown onion maggot. 



Fig. 5. Puparia of onion-fiy. Dorsal and ventral aspects. 

 Fig. 6. Female onion-fly. 



PLATE XI 



Fig. 7. Onions showing damage caused by the feeding of the maggots. 



Fig. 8. Aphacreta cephalotes. A parasite of the onion-fly. 



Fig. 9. Pupa of Aphacreta cephalotes. 



Fig. 10. Aleochara bilineata, a beetle whose larva is predaceous upon the pupa of the 



onion-fly. 

 All except Fig. 7 much enlarged. 



{Received February 9th, 1922.) 



