gradually are often subject to attack. After the wood has sea- 
soned from 4 to 6 months it is nearly always immune to attack. 
This group of borers causes heavy losses in rustic work and log 
houses, and in lumbering operations when trees cut during the 
winter are left lying on the ground throughout late spring and 
early summer. Cordwood and pulpwood are also damaged. 
The character of the frass, whether granular or fibrous or 
shredded, distinguishes certain species. 
1. Larvae found in coniferous trees _.0...... Ho ahs $5 
Larvae found in hardwood trees _...... LS yFiaee AEE ens cs 
2. Frass granular, closely packed behind larva 
Frass composed largely of fibrous or shredded material 
3. Frass pushed out through small hole... 
Frass tightly packed; filling entire mine behind larva 
4. Underside of head having four small tubercles 
Callidium antennatum hesperum, C. texanum 
Underside of head without tubercles... Oeme 
5. [piey presen cs Geeaeey ie er oe Physocnemum andreae 
In‘cedars, junipers; and Douelasir 33250 2 ee 
In pines and SUEUICES) oe ee a ne 
6. Larvae without ocelli and w jehout spines on lee sages 
Semanotus ligneus 
Larvae with 1 ocellus and with 2 small spines on last 
Ssepment ‘aADOVE: 2) =e oe Aue: Atimia confusa 
Head wider than long; Forni cylindrical 
Larvae with 2 small dorsal spines on last segment of 
body; mandible pointed at apex 
Asemum, Arhopalus 
Larvae without spines; mandible rounded at apex 
— Xylotrechus 
Head longer than wide; form depressed; ampullae velvety 
pubescent Me eats eo ae Acanthocinus 
8. Head wider than Wes 2 evel dorsal spines on last body 
SQOWMION GE ont es eae ee Asemum, Arhopalus 
Head wider than long and slightly keeled at sides: larvae 
very depressed . Stenocorus inquisitor lineatus 
Head longer than broad; last body ecement without dorsal 
spines ...... PO bone an Rome UI, Se ee _.. Monochamus 
9. Frass entirely ee Foe. Sete reat. er = 10 
Frass containing much fibrous material _ f 11 
10. Frass tightly packed behind larvae 
Larval pronotum smooth and white. Larval mines 
chiefly in the wood of ash, oak, and other hardwoods 
Neoclytus 
Larval pronotum covered with velvety, yellowish pu- 
bescence; larvae without legs; larval mines under 
the bark and in the wood Xylotrechus 
Frass exuded through small hole 
One ocellus on each side of the head; larvae yellowish 
and rather elongate; chiefly in hickory 
Knulliana cincta 
Ory 00 09 CLO 
~IS 
~l 
Two ocelli on each side of the head 
Elaphidion mucronatum 
174 
