92 THE ENTOMOLOGIST. 



in one or more places, especially towards the anal end, then it 

 extends to whatever may be in contact with the greasy surface ; 

 it may be to the paper of the saddle, box, or cabinet, or to the 

 hind wings if too close to the body ; or it may spread along the 

 abdomen, reaching the surface of the thorax and insertions of the 

 wings simultaneously, over both of which it may spread, until it 

 arrives at the pin, either at its ingress or egress, when it at once 

 commences business in earnest, and for the first time enters the 

 thorax itself, beginning its work of destruction by corroding the 

 pin (black enamelled pins not being always proof against its 

 attack, owing probably to some defect in the coating, as was 

 recently observed in examples of Macrogaster arundinis received 

 from a correspondent in the north) ; sometimes distending the 

 thorax, by chemical action on the metal of the pin, even to 

 bursting, as in a case of Sesia scolUformis now before me ; and 

 lastly, as Mr. Greene observes, it finds its way to the paper which 

 surrounds the pin. Such I believe to be the usual order of events 

 where a greasy specimen, especially if a bred male, of a greasy 

 species, is allowed to take its course without attention. 



Grease may, however, behave differently ; it may pass from 

 the abdomen to the hind wings, thence to the hinder half of the 

 fore wings. It may be only on one side, as in a case of A'", typhce 

 (before me), in which the abdomen, right hind wing, and hinder 

 half of right fore wing are saturated, the paper being stained by 

 the tip of the fore wing, while the thorax and left side are in 

 their normal state. In another case the hairs of the anal tuft 

 alone were greasy, the grease being communicated to the paper ; 

 and it is by no means uncommon to find the fore ^jart of the 

 thorax of an insect, otherwise as greasy as can be, untouched. 

 As to the points at which grease may become first visible, I have 

 been credibly informed, by one who ought to know, that the 

 centre of the fore wing is one of them. 



This brings us to the conditions under which moth-grease 

 may make its first appearance on the thorax, an occurrence 

 which may possibly be more common than is generally sup- 

 posed. It may happen when the insect has been transfixed 

 in the posterior part of the thorax, with the point of the pin 

 slanting backwards in such a manner as to pierce the meta- 

 phragm and enter the abdominal cavity, in which case a portion 

 of the pin passes through and remains in actual contact with 

 the grease, which it must be recollected is at that time in a very 

 soft state ; the insinuating oily matter of the ruptured cells, aided 

 by capillary attraction, finds its way along the periphery of the 

 pin, thus providing an outlet for the exit of the fatty matter as 

 it becomes disintegrated, which is thereby diverted from its usual 

 course, — the barrel is tapped, so to speak, — for it is surprising 

 how steadily the enemy follows the metal, when once it has 

 reached it ; and so, as the greasy mass becomes liquefied, it flows 



