256 



PINE. 



Giant Sirex ("Wood Wasp"). Sirex gu/as, Linn. 



Female " Wood Wasp " and maggot. Jaw of maggot, with four sharp, narrow 

 teeth ; and jaw of fly, with three broader teeth, both magnified. 



The splendid insect figured above is not usually credited 

 with doing much mischief in England, but from my own 

 observation I incline to think that this " Fir-wood Wasp," as 

 it is called in Germany (as well as another kind, the Steel Blue 

 Sirex or Siirx juvencus), is more often at work than is 

 supposed. The injury of the S. gigas is caused by the large 

 maggots boring galleries in the solid Fir timber. 



The female Sirex lays her eggs in various kinds of Pine — 

 Scotch Fir, Silver Fir, and Spruce — which, though not decayed, 

 are not in full health ; such, for instance, as trees past their 

 prime, or that have been uprooted, or broken by wind or 

 accidents, or are sickly from any other cause ; and it has been 

 considered, by some observers, that even an insignificant local 

 injury to the tree may afford a point for attack ; that the 

 females lay their eggs on such damaged spots, from which the 

 brood spreads, and thus in a few years an otherwise healthy 

 trunk is destroyed. The eggs are also stated to be deposited 

 in felled Fir trunks left lying in the woods. 



The female (as figured above) is furnished with a long ovi- 

 positor, by means of which she bores a hole through the bark 

 of the stem of the tree for the deposit of her eggs. 



The maggots from these are whitish, soft, and cylindrical, 

 with a scaly head armed with strong jaws ; a blunt point on 

 the tail-segment, and they have three pairs of very minute 

 feet. These larvae feed in the solid timber, and are full grown 

 in about seven weeks ; and then or later (for how long the 

 larval and pupal state last seems uncertain) they change to 



