492 



THE NATURE BOOK 



on page 491 it is seen extending beyond the 

 short blunt tail at the end of the abdomen. 

 This instrument readil}' distinguishes the 

 insect from a hornet, for the sting of 



1. Male. 



HORNETS. 



2. Queen. 3. "Worker. 



the latter is no more conspicuous than 

 that of a wasp. Furthermore, while the 

 sting of a hornet is a thing to be carefully 

 avoided, that of the Sirex need not be 

 feared. Indeed, it is not a sting at all, 

 but a complex boring instrument in a 

 two- fold sheath. The head of the borer is 

 provided with sharp, curved teeth, which 

 penetrate the bark and wood of fir trees. 

 A hole is then drilled by the borer, and 

 within the hole the insect deposits her 

 eggs. When egg-depositing these in- 

 sects may be easily captured, for the 

 withdrawing of the long ovipositor is a 

 slow process, and if the insect is removed 

 suddenly the ovipositor will be broken off. 

 The male insect, of course, does not possess 



this organ, and, consequently, more closely 

 resembles a hornet. 



From the eggs so deposited come wliitish 

 maggots or grubs which bore their way 

 into the solid wood of the tree, eating 

 out tunnels with their strong jaws in all 

 directions. The grubs often feed for three 

 years within the tree, eventually becoming 

 chrysalides near the openings of the tunnels. 

 The flies appear from the middle of July 

 to the end of November. 



Sometimes, for some reason, they re- 

 main in the chrysalis stage for long periods, 

 and if the infested tree should then be 

 felled, and the wood used for household 

 purposes, trouble often arises. Such, 

 indeed, was the cause of the invasion of 

 the grocer's shop referred to. As I sus- 

 pected, he had recently had some new 

 woodwork put into his premises, and that 

 w^as the origin of his " hornets' nest." 

 The time had arrived when the insects 

 should appear, and that they were then 

 located in a grocer's shop did not alter 

 that fact in the least ; the round holes 

 from which they had worked their way 

 out were visible in the woodwork to 

 pro\-e plainly whence they came. 



In the illustration on page 493 are shown 

 two examples of the Poplar Hawk-Moth 

 in their larval or caterpillar stage. (The 

 moth itself I ha\'e described in a previous 

 contribution, and illustrated on page 212.) 

 This larva is familiar in autumn as it cra\\is 

 down the trunks of trees, or about the 

 surface of the ground ; for at that period the 

 caterpillar is fuU-fed, and then leaves the 

 tree to bury itself beneath the soil, where 

 it will mould an o^'al-shaped chamber, in 

 \\liich it wiU moult its skin and become a 

 chrysalis. So it remains until May of 

 the following year, when it leaves the 

 cavity in the earth, and works its way 

 to the surface again. \\'hen it appears, 

 it is no longer a caterpillar, nor is it a 

 clir\-salis. for it has completed its meta- 

 morphoses and become a moth. At first 

 it looks a quaint object, all legs and body, 

 as it climbs the stem of a plant, or perhaps 

 the bark of the tree on which it fed as a 

 hungry caterpillar, but an hour later its 

 wings have fully developed in all their 

 wondrous hues ; the moth then appears as 

 shown in the illustration on page 212. 



The photograph shows well the distin- 

 guishing features of the caterpillar. Its body 



