222 MISC. PUBLICATION 657, U. S. DEPT. OF AGRICULTURE 
enlarging their mines until they are full grown, when they construct 
pupal cells near the surface. The same wound is utilized for years as 
a point of attack. This type of defect is easily recognized by the 
varying size of the open, darkly stained holes, ranging from 1%. to 
nearly 14 inch in diameter (fig. 45). For control of these borers see 
pages 27 and 38. 
The sapwood timber worm (//ylecoetus lugu- 
bris Say) 1s a slender rufous or blackish beetle 
from 10 to 12 mm. long. The larvae extend their 
round mines under the bark and crosswise through 
the sapwood of poplar, birch, and tulip, and the 
erubs are readily distinguished by the slender 
barbed spine on the ninth segment. 
Famity MORDELLIDAE 
The Tumblng Flower Beetles 
The representatives of the family Mordellidae 
are small, wedge-shaped beetles, with the head 
bent downward and the body strongly arched and 
prolonged posteriorly into a style, often spotted 
with yellow or silver. ‘They are generally dark 
colored and densely clothed with silky pubescence. 
These beetles frequent flowers, but are difficult to 
catch, as they jump, tumble, and run with such 
activity that they can scarcely be picked up. The 
larvae are white, soft-bodied, fleshy, and cylindri- 
cal, with a protruding pleural fold. The ninth 
abdominal segment terminates in a single truncate 
process or bears two recurved hooks. The legs 
are weak and conical. They have a globular head, 
a triangular mandible without a molar structure, 
a large hgula, and a labrum, but no gula. Some 
species of Mlordella, Tomoxia, and Mordellistina 
Ficure 48.— Holes feed in decaying wood, while other species of 
made by the  J/ordellistina bore in the pith of living plants. 
chestnut — timber N : fee Sine te i uhomtonecn 
one are of economic importance in the : 
worm ( Melittom- 
ma sericcum). but they are frequently taken by collectors. 
Faminies PTINIDAE and ANOBIIDAE 
The Death-Watch Beetles 
Famities BOSTRICHIDAE and LYCTIDAE 
The Power-Post Beetles 
The beetles belonging to the families Ptinidae and Anobiidae, the 
death-watch beetles, are small, seldom exceeding 5 mm. in length, 
rounded, convex, or odd-shaped forms, having the thorax extended 
hoodlike over the retractile heads, the antennae 9- to 11-jointed, often 
serrate or pectinate. The elytra are entire and cover the abdomen, 
