9548 Insects. 



October, but the greater number not until the following Maj'. Those 

 which become pupae in October emerge as perfect moths in the course 

 of a few clays ; they rarely, if ever, pass the winter in the pupa state, 

 and it is a very remarkable and hitherto unexplained fact, but one 

 which I have dwelt on at some length in a paper read before the 

 Entomological Society, that the female moths which are disclosed in 

 October and do not hybernate are almost invariably barren : I say 

 almost, because I do not desire to press this theory unduly; as far as 

 my observations have extended they are afwat/s barren females, 

 and therefore entirely useless as regards the continuance of their 

 tind. This is by no means an isolated case of the superabundant 

 supply of life provided by Nature ; the autumnal production of drones 

 in bee-hives, not one in a thousand of which ever serves any useful 

 purpose, as far as apiarians have ascertained, is a similar instance of 

 the lavish abundance Nature supplies, and the destruction of these 

 drones by the workers is a striking instance of the mode in which she 

 disposes of this superabundance. These barren moths are not merely 

 of necessity unproductive from the absence of males, but their bodies 

 are perfectly empty, mere hollow cavities without eggs or any per- 

 ceptible ovary. 



If the winter prove severe the larva; retire entirely beyond the reach 

 of frost, returning towards the surface again as soon as the thermo- 

 meter rises. 



The bulk of the brood emerges in June, and then the sexes are iu 

 equal numbers, and the females are invariably fertile, their bodies 

 being filled with eggs. A vast and incalculable amount of injury 

 accrues from this hybernation of the caterpillar. The hybernation of 

 caterjjillars is a very familiar fact to entomologists; but they live 

 through the winter in a quiescent state, as though slumbering, and do 

 not eat, simply because their usual supply of food has failed; the 

 leaves have fallen, and they are compelled to wait until s])ring has 

 produced a fresh supply. But in the case of these turnip giubs it is 

 very different: their food, being roots, is to be fotuid at all seasons, 

 and the work of destruction goes on incessantly, and is only limited 

 by the suppl}' ; indeed the various agricultural roots are often har- 

 vested with the enemy concealed in the interior. 



There is small need for me to dwell on the injurious character of 

 this insect; e\ery fanner and every gardener must have been con- 

 vinced of this during the dry summer and autumn of 1864. The great 

 cause of the evil may be traced to the use of poisoned wheat, provided 

 intentionally for the rooks, and perhaps unintentionally, but certainly 



