312 INSECTS AT HOME. 



On Plate IX. Fig. 7, is shown one of these remarkable Saw- 

 flies, called Sirex or Urocerus juvencus. The specimen is a 

 male, so that the very long- ovipositor is not shown. In this 

 genus the neck is a very short one, there are two marginal and 

 four sub-marginal cells, the maxillary palpi are very short, and 

 the boring instrument is very long, and exterior to the body. 

 The colour of tlie present species differs greatly according to 

 sex, the male being black and yellow, while the female is a 

 very deep violet, almost amounting to black. 



I very strongly recommend any of my readers who may obtain 

 a female Sirex to disengage the actual borer from its two-bladed 

 sheath, and examine it with the aid of a microscope. A half- 

 inch object-glass will give quite sufficient power. It is straight, 

 stiff, and elastic, as if made of steel, and, if bent, will spring 

 back to its proper form with the elasticity of a Toledo rapier. 

 In form it somewhat resembles the instrument known technically 

 as a ' rymer,' except that the edges are rounded, and not square. 

 But the borer possesses an auxiliary cutting apparatus which 

 places it far above the rymer in point of efficacy. Even with 

 an ordinary magnifying lens, it is easy to see that the end of 

 the borer is developed into a sharp head very much resembling 

 that of a boarding-pike, and that the outline of the shaft is 

 broken into a series of notches. 



The half-inch glass, however, discloses a marvellous example 

 of mechanical excellence. The head of the borer is then seen 

 to be armed with long, sharp teeth, slightly curved inwards, 

 and acting just as does the carpenter's ordinary centre-bit. 

 So much for the head of the borer : we will now turn to tlie 

 shaft. It appears that, in order to make a clean-cut hole for 

 the reception of the egg, the shaft of the borer has to finish the 

 task which the head begins. Accordingly, it is armed on each 

 of its sides with a series of hard, sharp-edged ridges, running 

 diagonally across it, and acting exactly as do the sharp ridges 

 of a coffee-mill. A more effective implement could not have 

 been invented, and the various boring instruments of modern 

 days, however novel they may appear to be, are in reality formed 

 on exactly the same principle as the borer of the Sirex, though 

 perhaps they may not carry out their object with such perfection. 



This is a wood-boring insect, the female drilling a hole in the 

 lolid wood, usually that of the fir, and depositing her eggs in 



