262 MISC. PUBLICATION 657, U. S. DEPT. OF AGRICULTURE 
prionus (P. californicus Mots.) is economically as important as P. 
imbricornis. It occurs throughout the southern Rocky Mountains and 
the Pacific States, chiefly in oaks but also in sumac (?hus) and other 
shrubby plants. The broad-necked root borer (P. laticollis Drury) 
occurs most abundantly through the Northeastern States. Its habits 
are similar to other species of Prionus, but it 1s more commonly found 
on smaller trees, fruit trees, and shrubs. P. pocularis, the pine-stump 
prionus, is the only species of this genus that has not been found in 
living trees but only in dead coniferous logs and stumps. It occurs 1 
the Middle Atlantic and Southern States and is of little economic im- 
portance except occasionally in cross ties. It is rarely abundant 
enough to do any serious damage to timbers in use. 
Ptychodes trilineatus (1.), the fig-tree borer, is a large, elongate 
beetle, from 18 to 25 mm. in length, and widest about the middle. 
It is uniformly grayish in appearance, marked with small, reddish- 
yellow spots and has three irregular, white stripes along the entire 
body, one median dorsal and one on each side. The Jarva is an 
elongate, robust, cylindrical borer having the head very flat and 
longer than wide. ‘The posterior portion of the pronotum is dark, 
velvety pubescent, and the dorsal ampullae bear four rows of shining 
tubercles. Beneath the anal lobes occur a group of 5 to 8 short acute 
spines. Legs are present. It feeds in the trunks and branches of living 
and dying fig trees and occasionally im alder, excavating mines in the 
wood and exuding fibrous frass. It is found in the Southern and 
Southwestern States. 
The females lay their eggs early in summer in small holes gnawed 
through the bark. For some time after hatching each larva feeds 
beneath the bark, often girdling the limbs before entering the heart- 
wood to make a long mine, at the top of which the pupal cell is 
constructed. Much frass is exuded by the larva, and the adult 
gnaws the exit hole. Several years are normally required to com- 
plete the development. These larvae seriously injure figs and alders, 
often killing branches or small trees. For control of this borer see 
page 24. 
Stenocorus lineatus Oliv., the ribbed pine borer, is a rather robust, 
dark beetle from 13 to 18 mm. im length, completely mottled with 
grayish pubescence. The thorax 1s cylindric ‘al, bearing a spine on 
each side, and the elytra each bear three strongly raised lines. The 
larva is elongate and very depressed, having a flat, extended head 
wider than long, with mandibles deeply notched at the apex. The 
pronotum is smooth and : shining, and the ampullae are dull, finely 
pubescent, and feebly tuber culate. Legs are well developed. 
Very early in spring the adults emerge and lay the eggs in crevices 
of the bark of dead pines and many other conifers cut or dying during 
the winter. The larva feeds entirely beneath the bark, filling the 
space with ereat quantities of fibrous frass. Late in the summer it 
constructs an oval nesthke pupal cell (fig. 54, 7) of fibrous frass and 
an exit hole extended almost through the bark, then pupates and 
transforms to an adult, overwintering in this form. 
The species is found throughout the United States, but is of no 
economic importance, as it never injures the wood. It is mentioned 
because of its abundance and because it is so frequently found along 
with injurious species. 
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