FOREST IMPORTANCE OF MYELOPHILUS MINOR HART. 
233 
entomologist and forester the distinction between the two, as shown by their work, 
is extremely easy. 
In conclusion, it is with great pleasure that I acknowledge the help, advice, 
encouragement, and facilities which have been given me by Dr R. Stewart 
MacDougall throughout this work. 
DESCRIPTIONS OF FIGURES OF M. MINOR. 
Fig. 1. The smaller pine beetle, Myelophilus minor Hart. Adult. (Greatly magnified.) 
Fig. 2. Prothorax of M. minor. (Greatly magnified.) 
Fig. 3. Prothorax of M. minor var. (Greatly magnified.) 
Fig. 4. Apex of elytra of M. minor. (Greatly magnified.) a = second interstice. 
Fig. 5. Apex of elytra of M. piniperda. (Greatly magnified.) a 1 = second interstice. 
Fig. 6. Hind leg of M. minor. (Greatly magnified.) a = base of tibia ; 6 = tooth about centre of tibia ; 
c = apex of tibia. 
Fig. 7. Hind leg of M. piniperda. (Greatly magnified.) a x = base of tibia; b ± = middle of tibia; 
c x = apex of tibia. 
Fig. 8. Larva of Myelophilus minor, side view. (Greatly magnified.) a = head ; b — thorax; e = 
abdomen; e. = epipleural fold; h. = hypopleural fold; i. = infra-anal lobe; M. = mandible ; Mx. = maxillae ; 
р. = prescutal fold ; pa. = para-anal lobe ; Sc. = scutal fold ; Sp. = spiracle ; Sr. = scutellar fold ; St. = sternellar 
fold ; Stt. = supra-anal lobe. 
Fig. 9. Head of larva, M. minor, seen from above. (Greatly magnified.) a. = antenna ; c. = clypeus; 
e. = epistome ; ep. = epicranium ; e.s. = epicranial suture ; /. = frons; /.s. = frontal suture; l. = labrum ; 
m. = mandible. 
Fig. 10. Region of epistome, M. minor larva, a. = antenna ; c. = clypeus ; ep. = epistome ; /. = frons ; 
l. = labrum. 
Fig. 11. Maxillae and labium of M. minor. (Greatly magnified.) G. = cardo ; l. = ligube ; l.l. = lacinial 
lobe; l.p.= labial palp; M. = menturn ; M.p. = maxillary palp; S. = stipes ; S.a. = submental area; S.m.= 
submentum. 
Fig. 12. Pupa of M. minor, ventral view. (Greatly magnified.) a. = antenna; c. = coxa of front leg; 
с. x = coxa of middle leg ; c.s. — caudal spine ; d. = coxa of hind leg ; e. = eye ; el. = elytra ; /. = frons ; fe. = 
femur; f.s. = frontal spines; f.sp. = femoral spines; g. = gena ; h. = femur of hind leg; i. a. = inter coxal 
area ; l. = labrum ; li. = labium ; m. = mandible ; ms. = mesosternum ; mt. = metasternum ; mx. = maxilla ; 
o. = medial groove ; r. = tenth abdominal segment ; w. = flying wing. 
Fig. 13. Galleries of M. minor and M. piniperda on a thin-barked piece of Scots pine stem; the 
pupation in the case of M. minor larvae has taken place in the wood, a = mother gallery of M. piniperda ; 
a x = mother gallery of M. minor-, b = larval gallery of M. piniperda-, h 1 = larval gallery of M. minor ; 
c = pupal' chamber of M. piniperda ; c 1 entrance to pupal bed, M. minor ; d = entrance to mother gallery, 
M. piniperda ; d l = entrance to mother gallery, M. minor ; e = exit hole through which a young M. minor 
adult had escaped from its pupal chamber. 
Fig. 14. Piece of pine bark with crowded workings of minor ; pupation of the minor larvae here took 
place in the bark; the inverted U-shaped gallery is an irregular piniperda gallery, the irregularity being due 
to overcrowding. 
Fig. 15. Galleries of M. minor made on a piece of felled pine stem: the long arms have been formed 
in a direction away from the sun. 
Fig. 16. Male reproductive organs of M. minor. (Greatly magnified.) A. g. = accessory gland; G.d.= 
common duct ; F. = fork ; Fe. = a femur of penis ; P. = penis ; R. — ring ; S. = sheath ; S.v. = seminal vesicles ; 
T. = testes ; V.d. = vas deferens. 
TRANS. ROY. SOC. EDIN., VOL. LII., PART I (NO. 10). 
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