88 THE CANADIAN ENTOMOLOGIST 



either in an irregular area around the egg or in a gradually widening, elongate 

 area away from the egg and parallel to and against the leaf edge. 



Practically all of the ovatus eggs in our cages and many in the field were 

 parasitized by Closterocerus cinctipennis Ash. In the cage containing forty-five 

 aerosus eggs, nineteen mines were started, 17 eggs were parasitized and nine 

 appeared to dry up. In the cage containing thirty-five aerosus eggs, ten mines 

 were started, fifteen eggs were parasitized, and ten failed to hatch for some 

 reason or another. Most of the larvae which started the mines were also parasit- 

 ized by the same species. Parasitized eggs became black in colour and many 

 such were noted in the field. A few good eggs were noted as late as July 15, 

 showing that egg deposition evidently extends over a considerable period. 



Full grown larva of B. ovatus. Length 7 to 9 mm. Width of first 

 thoracic segment 2.4 to 2.85 mm. Slightly wedge-shaped, much flattened. 

 Body composed of thirteen well-defined segments which are deeply notched and 

 lobed. Head and mouth-parts dark. Head more or less retracted into first 

 segment. First segment as broad or slightly broader than the following, body 

 gradually tapering to the twelfth segment. First segment with large, well- 

 developed, comparatively smooth, shining, subquadrate plate on both dorsal 

 and ventral surfaces. Dorsal plate with median line groove. Abdominal seg- 

 ments one to seven with pronounced rounded lobes. Lobes of abdominal seg- 

 ments five to nine each bearing a group of several stout, minute spines. Posterior 

 dorsal edge of eighth abdominal segment fringed with row of minute, stout 

 spines. Colour whitish, broad median dorsal line indicated on abdominal 

 segments one to eight. Lateral dorsal portion of each body segment except 

 the first varies from light gray in some specimens to black in others. (Immature 

 specimens are entirely whitish). Entire dorsal surface except plate of first 

 segment covered with somewhat slightly raised dots. These are more apparent 

 laterally and bear the dark colour. Ventral surface somewhat similar to dorsal. 

 Entire lateral surface of body sparsely hairy. 



The larva of B. aerosus appears to be somewhat similar to the above, except 

 that it is smaller (Length 4-5 mm. Width of first segment 1.53 mm.), and that 

 the sides of the body appear to be slightly rougher, and the spines on the lobes 

 of the fifth to ninth abdominal segments appear to be less pronounced. 



Pupa of B. ovatus. Length 6.7 mm. Greatest width 3.5 mm. Colour 

 brown ochre (Nomenclature of Windsor & Newton's Water Colours). Shape 

 similar to that of the adult. Surface smooth, shining. 



This stage is probably passed on top of the soil in rubbish or under the 

 surface of the soil. Many mijies were examined in the field, but no pupa were 

 ever found. It was noted that in every case, the larva had made its exit through 

 the lower surface of the mine. In our cages only one larva of ovatus pupated, 

 and it did so on the surface of the soil. When full grown they left the mines, 

 and for some reason or another all except one died on the surface. 



Ovatus was described by Weber in 1801 (Observ. Ent., Vol .1), and aerosus 

 by Melsheimer in 1846 (Proc. Acad. Nat. Sc. Phila., Vol. 2). There is some 

 synonymy indicated, but this need not be gone into here. 



