badly weakened condition. Horntail larvae are parasitized by several members of 
the ichneumonid genera Rhyssa and Megarhyssa. Members of the latter genus are 
of special interest because of their striking appearance. Using their extremely long 
Ovipositors, the females bore deep holes into the wood and deposit their eggs on or 
near horntail larvae in their galleries. The ovipositor often becomes caught in the 
wood and the female, unable to escape, dies. M. atrata (F.), M. macrurus macrurus 
(L.), and M. greenei Viereck are parasites of Tremex columba (L.), but not of any 
other horntails. 
Horntail adults are medium to large in size and are usually metallic blue or black. 
Some are varicolored with combinations of black, red, and yellow. The head, 
thorax, and abdomen are of equal width; the wings are well developed; the antennae 
are long and filiform, with about 15 segments; and the anterior tibia is armed with a 
single apical spur, cleft at the apex. 
Damage caused by members of the family can be prevented or reduced by 
promptly using infested logs or submersing them in water, and by kiln-drying green 
lumber sawed from infested logs. 
The genus Sirex is represented by four eastern species. S. juvencus (L.) occurs in 
eastern Canada and the Northeastern and Midwestern States. Its hosts are listed as 
pine, fir, and spruce. Canadian studies indicate that S. juvencus larvae do not 
develop in the absence of the fungus, Stereum chailletii (Pers.) Fr. (1159). In New 
Brunswick, the males precede the earliest females by 2 to 4 weeks, before each of 
the sexes continues emerging sporadically throughout the summer. Peak emergence 
continues for a month from mid-August. Oviposition begins within a day of 
emergence; a 2- to 10-mm puncture into the sapwood is completed in about 8 to 10 
minutes. One to three eggs are deposited at intervals along the oviposition site. 
Eggs or early-stage larvae overwinter. Pupation occurs after 5 to 11 molts, and the 
pupal stage lasts 4 to 6 weeks. It takes 2 to 3 years for S. juvencus to complete its 
life cycle (1/59). The blue horntail, S. cyaneus F., attacks spruce, larch, and pine 
in southern Canada and the northern tier of Eastern States. S$. edwardsii Brulle has 
been taken from pitch pine in the Atlantic Coast States and is recorded from Quebec 
to Georgia west to Saskatchewan, Wisconsin, and Arkansas. S. nigricornis F. has 
been recorded from shortleaf, eastern white, and Virginia pines and 1s distributed 
from Quebec to Florida west to Saskatchewan, Wisconsin, Arkansas, and Loui- 
siana. 
Sirex areolatus (Cresson) has been introduced from western North America into 
the Southeastern United States, but may not have become established. 
The genus Urocerus Fourcroy is represented by four eastern species. U. albicor- 
nis (F.), the whitehorned horntail, attacks many species of conifers and occurs 
throughout boreal America. Adults are blue-black or black and about 25 to 30 mm 
long. The middle of the antennae, cheeks, bases of the tibiae, and tarsi are white. 
White spots also occur at times on the sides of the abdomen. This species has also 
been observed attacking freshly sawed lumber. U. gigas flavicornis (F.), the yellow- 
horned horntail, attacks spruce and other conifers in New England and Canada. 
Adults are black and from 20 to 37 mm long. Females have the first, sixth, and part 
of the seventh abdominal segments yellow; males have the second through fifth 
segments orange-yellow. The fungus, Stereum chailletii, is also associated with this 
siricid (1159). U. cressoni Norton, the black and red horntail, occurs from 
eastern Canada to Florida, west to Wisconsin and Minnesota, and breeds in fir, 
spruce, and pine. U. taxodii (Ashmead) infests baldcypress in Florida. 
The pigeon tremex, 7remex columba (L.), 1s the most common of the horntails. 
410 
