416 BIONOMICS OF CERTAIN HYBIENOPTERA PARASITICA. 



Plate 25. 



Fig. 7. The Hj'perparasite, Mesochorus palUdus (Brisch.), adult male, x 8. 



Fig. 8. Ovipositor showing terminal region of body, ovipositor sheath {SH.) and stylets 

 {8TIL). 



Fig. 9. Cocoon of Microgaster connexus which had been liyperparasitized by Mesochorus 

 pallidus, and from which the latter had emerged by making a rough hole at X. 

 At F is the faecal pellet voided by the larva before pupation ; it will be noticed 

 that the fsecal pellet in fig. 9 is larger than that in fig. 1. x 8. 



Fig. 10. Terminal abdominal region drawn from a larva preserved in an osmic-acid fixative. 

 The fat is blackened. At HP. HP. the hyperparasite is cut across in two 

 places. The two transverse sections have been schematically joined together by 

 lines behind the gut, as the hyperparasitic larva was bent around the gut in the 

 form of a half-circle. The enigmatic tubular glands (Malpighian tubes) were 

 not cut in this obliquely sagittal section, but the left-hand one has been drawn 

 in diagrammatically at Tx. X 60. 



Fio-, 11. Transverse section of metathorax showing hyperparasite at HP^ X. The last pair 

 of imaginal discs of the legs are cut at 7D3. X 70. 



Fig. 12. Four cells of the terminal vesicle drawn from such a part as that enclosed by a 

 square in fig. 10. X 510. (Fixed in KaCraOT of 3 per cent.) 



Fig. 13. Hypoderm of body-wall. X 510. 



Fig. 14. Vesicle cells fixed in alcohol-acetic-acid fixative, x 300. 



Plate 26. 



Fig. 15. Three-quarter grown yija/izs ^o?)u', whole preparation (paracarmine) ; shows parasitic 

 larva {AphicUus sp.) at P, in optical section. Below is drawn the upper (tail) 

 region of the parasitic cyst, to show the embryonic membrane (SA). X 00. 



Fif. 16. Very young larva of Microgaster connexus showing embryonic membranes at S 

 and at A. x 222. 



Figs. 17 & 18. Two diagrammatic drawings illustrating the manner in which certain 

 Braconids (Apliidiidse) attack Aphids. In fig. 17 the abdomen of the Aphid 

 faces the observer and the parasite is attacking from the side. In fig. 18 it is 

 attacking from the back, the usual way. 



Fig. 19. High-power drawing of the region X in fig. 20. Below is the heart {H), at OL is 

 the opening of the vesicle gland. Dorsal surface of body to the right, ventral 

 to the left. X 300. 



Fio-. 20. Gives the key to the position of the drawing in fig. 19. See text, p. 398. 



Fig. 21. Transverse section of vesicle gland. X 510. 



Fig. 22. Transverse section of posterior region of vesicle, showing enigmatic tubular gland 

 (Malpighian tube'?) at Tx, vesicle glands at GL, and heart at H. x 95. 



Fio-. 23. Part of the transverse section of the enigmatic tubular gland (in fig. 22 at T.v) 

 drawn at a high power, x 510. 



Fio-. 24. Schematic figure of structure of half-grown larva of Microgaster to show nerve- 

 cord ending near NY, and the disposition of the other organs. 



Fio-. 25. Young larva of M . connexus showing the arrangement of the later embryonic 

 organs, the segmentation, the embryonic membranes {S & A), and the vesicle in 

 an earlv stage, x 95, 



