AKT. 1.'3. BLISTER BEETLE TRICRANIA PAEKER AND BOYTNG. 39 



Plate 2. 

 Head i^tructures. 



Fig. 13. First iustar. — Ventral view. 



14. Second instar. — Ventral view. 



15. Fourth instar. — Ventral view; m, nieutuni ; .s»(. snhmeiituin ; (ju. gula. 



16. Fourth instar. — Dorsal view. 



17. Fifth instar. — Ventral view. First pair oi' vestigial legs shown ; a, 



antenna ; la, nasale=the fused labrum, clypeiis and anterior margin 

 of frous; lot/., leg; li, labium; ind, mandible; wu', maxilla. 



18. Fiftli instar. — Dorsal view. 



19. Sixtli instar. — Ventral view. 



20. Sixtti ///.s^/r. -Dorsal view; cli/. clyijens; hi/, byiiopli.-u-nyx ; la, labrum. 



Plate 3. 



Eggs and Larval Instars. 



Fig 21. Cell of the bee CoUctes ruflthora.r Swenk with fourth larval instar of 

 Tricrania inside. Notice the unbroken covering of the cell and the 

 great amount of excrement-pellets of the Meloid larva. The honey 

 supply is exhausted. 



22. Eggs of Trivrania. Cement spots on the egg-shells. 



23. CoUetes rufitliorax, female, with first instars of Tricrania. just having 



attached themselves to its hair. Drawn from a specimen in cap- 

 tivity; in nature the larvae are found mainly clinging to hah-s on 

 the posterior, dorsal part of the head or on the vertex. 



24. First instar of Tricrania grasping a bee's hair with its mandibles, the 



legs having nothing to do with this performance. Compai-e fig. 4. 



Different instars of Tricrania. 



All figures and the interposed millimeter-scales drawn with the same magni- 

 fication to demonstrate the growth of the larva and to indicate the real .'^ize 

 of the instars. wKZ.=mandible. 



Fig. 25. First in -star. 



26. Second instar, first period. 



27. Second instar, second period. — Notice that head and legs have the 



same size as in fig. 26. 



28. Third instar, first period. — Lateral and ventral views ; c. s. 2, cast 



skin of second instar. Compare the size of head and spiracles with 

 the size of the same structures in figs. 27 and 29. 



29. Third instar, second period. 



30. Fourth instar, first period; c. s. 3, cast skin of third instar. Notice 



the dorsal sclerite of prothorax, not developed in third instar. 



Plate 4. 



Various instars. 



Fig. 31. Fourth instar. second period. 



32. Sixth instar (6), enveloped by the exuvia of fifth (5) and fourth (4) 

 instars. In nature both exuvia are unbroken and placed against 

 each other and against the sixth instar; in the figure they are cut 

 open, pulled out and partly separated. 



