190 FOREST ENTOMOLOGY. 



The female Sirex, which is armed with a long ovipositor, lays her 

 eggs ill Scots pine and silver fir trees which are either sickly or 

 injured. The full life-history does not seem to have been worked 

 out, either by German or English entomologists, but it is said that the 

 larvae attain their full development in about seven to eight weeks, 

 but that they live from two years in the larval stage, and appear as 

 perfect insects the third year. They make a sort of rough semi- 

 circular route, at first boring deeply into the wood, and then turning 

 towards the outside, in fact often just immediately within the bark. 

 Although the perfect insects do not appear until July, both sexes 

 may often be found within the logs in November as jjerfectly devel- 

 oped insects. One of the best consignments of those insects I ever 



Fig. 1S2.— Siivx gigas (mule), Fig. 181.— Sirex gigas (feriude), 



reduced. reduced. 



had sent was captured by a miner issuing from props within the 

 coal-pit. 



The larvce are whitish and soft. The head is scaly, and armed 

 with strong jaws, and there is a blunt hook at the extremity of the 

 tail segment. They are about 1^ inch in length, and about | to |- 

 inch in diameter. I have never found any pupal stage except as 

 tightly packed forms of the perfect insect. 



The female (fig. 181) is usually 1| inch in length from head to ex- 

 tremity of ovipositor, and about ^ to | inch in breadth. The antennse 

 are filiform, yellow, and 18- to 25-jointed. The head is black and 

 hairy ; eyes and ocelli black. There are two yellow portions behind 

 each eye. The thorax is wholly black and hairy. The abdomen is 

 made up of nine joints, the colour being banded of yellow and black. 



There is a black velvety band across the middle of the abdomen, 

 on either side of which there is a yellow band, the abdominal segment 



