GIANT SIKEX. 257 



chrysalids in the tree. The pupa resembles the perfect insect 

 lying still, soft, and white, with the limbs laid along the breast 

 and body. 



The further change to the complete insect may occur in a 

 month, but if the maggot has not turned to the chrysalis till 

 autumn the fly will not appear till the following summer, or 

 even a much later period. 



The female Sirex is usually an inch and a half long, 

 cylindrical, and with the head and the rest of the body of the 

 same diameter. The colour is black, banded with yellow on 

 the first two rings of the abdomen (the first of which is 

 brownish at the base). The last three rings of the abdomen 

 are also yellow, with some amount of brownish at the base of 

 the last segment. There is also a yellow spot on each side of 

 the head. The abdomen has a strong blunt point at the tip, 

 and underneath it is furnished with the ovipositor, which 

 is long and black, and lies in the yellow sheath shown in 

 the figure (p. 256). The thighs are black, the shanks and feet 

 yellow, and the four large membranous wings are of a brownish 

 yellow. 



The male is smaller, with the abdomen flatter and yellowish, 

 excepting the first segment, which, as well as the last segment 

 (or end of the tail) and its appendage, is black. The hind pair 

 of shanks and feet are black or dusky ; pale, or with yellow 

 rings at the base. The horns are yellow ; those of the male 

 are nearly as long as the body, those of the female are rather 

 more than half that length. 



Prevention and Eemedies. — The best methods of prevention 

 are to clear away trees that are in a condition to attract 

 attack — such as trees that have been injured by accident or 

 ill-treatment, or that are weakened by disease or attacks of 

 other insects, and also those that have been blown over or 

 that have been felled, as the Sirex lays its eggs in felled as 

 well as in standing timber. 



Any trees which are found to be infested (either by the Sirex 

 being seen escaping, or by the large holes in the trunk showing 

 the escape to have taken place) should be felled and disposed 

 of according to their condition, so as to stop further spread of 

 the insect from them. 



If they can be taken to the saw-pit and converted to any 

 rough use it is best, for thus the infested parts may be cut off 

 and burnt, and the sound timber preserved ; but if this 

 cannot be managed, something should be done, both with 

 trees in this state and felled trunks lying in the woods, to 

 prevent the insects escaping. 



If nothing else occurred the tree might be split for firewood 



s 



