994 MISC. PUBLICATION 657, U. S. DEPT. OF AGRICULTURE 
KEY TO MORE IMPORTANT POWDER-POST LARVAE 
The four families and their more important genera, into which the 
larvae are usually divided, are characterized and separated in the 
following key. The genera and species are not described, because they 
have not been thoroughly worked up and are difficult to characterize 
on the basis of present knowledge. 
Ihe Head almost entirely protruding from the prothorax; mandible 
usually dentate; terga usually hairy or asperate_______________ 3 
Head deeply embedded in prothorax, cutting edge of mandible 
gougelike, rarely toothed; terga never asperate______-___-____- 2 
2. Last abdominal spiracle much larger than all others; mandible with 
a fleshy process on dorsal inner’ edge_______-___2____=— Lyctus 
Last abdominal spiracle not abnormally large; mandible with or 
without tleshiylObe= tie xcs) eaten he eee tee Bostrichidae 12 
3. First spiracle pushed forward into anterior margin of prothorax; 
terga without asperities; usually found in stored plant material, 
seed: etGle 2 S258 SaaS ae Sr hk ee ee Ptinus 
First spiracle between prothorax and mesothorax; terga usually 
asperaite. = 22 = a2 Shee Se eS Be ee ae 4 
4. Chitinization between labium and mentum narrow and U-shaped 
or lacking: malaxdivided== == - > oe ee ee eee 5 
Chitinization arrow-shaped and pointing posteriorly; mala simple, 
no inner lobe; spiracles large, annular without spoutlike projec- 
tion Prom .Side = S275 Sr aE Spee ee ae Bee ee Ptilinus 
5. Inner lobe of mala consisting of a strong curved spine_ _Xestobium 
Inner lobe of mala fleshy, usually with several smaller spines or setae_ 6 
6. Inner lobe of mala smaller than outer. Spiracles with a short or 
long-spoutlikejprocess# | 22222. See 2 Ee Re eS cee a 
Inner lobe of mala about as large as outer; spiracles with a short 
spoutlike: processau. =o Sse ae a ee 9 
(fp Claw short and curved; a fleshy lobe at base; feeding in stored plant 
productssand seeds 322 4 Safes ee ee ee eee Lasioderma 
Claw usually slender, no lobe; wood borers________...-.-_--___- 8 
8. Spiracles with long spoutlike process; mandible with 3 lateral teeth 
On dorsal-edees 20025 5 Se aie ee ee eee Anobium 
Spoutlike process on spiracles only indicated; each side of prothorax 
bearing curved rodlike impression. 
Mandible with three lateral teeth__..._..._..-- Hadrobregmus 
Mandible with two lateral teeth_____..._-..___- Microbregma 
9. Labrum about twice as widetasdong== === 22s eee ae Ernobius 
Labrumyabout asi widevas orgs see eee eer eee 10 
10. Tergal asperities in about two transverse rows__---.---- X yletinus 
Tergal asperities in about four transverse rows___.-.-.---_--__-- 11 
tue: Posterior tergal fold with long soft hairs_____________- Nicobium 
Posterior tergal fold densely beset with short spinelike hairs 
Trichodesma 
12. Mandible with a large grinding lobe and a soft fleshy lobe on upper 
inner margin; no impressed line on side of prothroax; tarsi all 
bearing. chitinized Claws 2 322 S55 eee 13 
Mandible without chitinous or fleshy lobe; a curved impressed 
line on side ef prothorax, usually only first tarsal claw chitinized_ 16 
13. Prothorax bearing a chitinized tubercle in front of spiracle; no 
ocelli: cutting, edge of mandible entires = ae eee 14 
No tubercle; ocelli present; cutting edge of mandible dentate____ 15 
14. Inner edge of molar lobe of mandible carinate________ Heterarthron 
Inner edge of molar lobe of mandible smooth__________~_ Polycaon 
15. Sixcocelli? breeds imi comilercst ss eee eee Stephanopachys 
Breeds. 1n-bamboos. S22 Sls es ee eee ee Dinoderus 
16. Maxillary mala without projecting style or spine on inner edge; 
labrum: trilobed2 22 202255 se ee ee ee 17 
Maxillary mala with a free projecting style or spine on inner edge; 
labrum ‘entire 27. -<i. 2) oe ee ee ple. Sens eee 18 
