158 MISC. PUBLICATION 278, U. 8S. DEPT. OF AGRICULTURE 
red or marked with yellow. It is found in pines, firs, and spruce 
throughout the West. S. aerolatus Cress. is another metallic-blue 
species (fig. 78), with black legs and smoky wings. This species 
commonly attacks redwood, cypress, and cedars, but it is also found 
in pines, firs, and other conifers. S. behrensti Cress. is a smaller 
species, five eighths of an inch in length, with head and thorax blue 
black and the apical segment of the abdomen reddish brown. The 
larvae infest ponderosa pine and sugar pine and have been found 
also in Monterey cypress. 
Z 
Za 
ji 
Z 
ig: 
Ze 
q 
H 
y 
ae PEN 
TO 
. 
ANWWARUAAININNNNNNUNN 
FIGURE 79.—Hemlock bark maggot (Cheilosia alaskensis) : m, Resin mass with exit hole, 
adult fly having emerged; n, longitudinal section of similar mass, showing wound in 
inner bark and outer sapwood, pupal chamber and exit hole in outer pitch mass, and 
original beetle entrance connecting them; o, healing wound in inner bark beneath mass 
like that shown at m; q, longitudinal section of wound p; r, maggot; s, puparium; f, 
pupa; uw, adult male; v, head of female; w, head of larva; £, antenna. 17, s, t, u, and 
WF XD De 20a XS 455 a CBurkes) 
Xeris caudatus Cress. is a very long, slim species, with an ovi- 
positor as long as, or longer than, the body. The abdomen is wholly 
black and the legs yellow. The favorite host apears to be lodgepole 
pine. X. morrisoni Cress. is similar but has a reddish abdomen. 
It attacks firs and lodgepole pine and probably other conifers. 
BARK MAGGOTS 
Pecular defects in the lumber of certain coniferous trees, con- 
sisting of dark-brown or blackish resinous scars, with the wood 
thickened and curled, are made by bark maggots of the genus 
