6192 



Northern Entomological Society, 



what undiscovered clear wing always turns to a red-legged Ichneumon ? These 

 cocoons always occur in the usual mines of Cossus, soraelimes in oak, commonly 

 in willow, always very near the outer bark, always compact, tough, plentifully pro- 

 vided with silk, abundantly intermixed with the carpenter's chips ; the Cossus grub 

 was never more aptly described than when he was called Xyleutes or the car- 

 penter. Only one entomologist to whom I have shown these cocoons was aware of 

 their true nature, and that entomologist was Mr. Bond, a gentleman second only to 

 Mr. Doubleday himself in his knowledge of the preparatory states of British 

 Lepidoptera. 



" Let us return to the cocoons. I have said they invariably produce Ichneumons 

 which are always of one species. Does it then follow that when the larva of Cossus is 

 stung by an Ichneumon, it invariably becomes dwarfed, and, dwindling to the dimen- 

 sions of a moderate-sized Sesia, terminates its existence in this aborted form ? Certainly 

 not as a rule ; on the contrary, the largest cocoons frequently produce Ichneumons, 

 giving no indication of the contained parasite until he vibrates his iridescent wings on the 

 exterior of his prison-house. The mystery admits of another solution. The larva 

 of Cossus is of slow growth and of long life ; some say it lives four years, some three, 

 some two. Mr. Standish tells me he kept some larvae after they seemed full-grown 

 between three and four years ; and that they pertinaciously and obstinately refused 

 to chryssle at all until at last he threw them away, utterly disgusted with their 

 seemingly unnatural conduct. Now, these insect Methuselahs are infested by a para- 

 site which never enjoys the pleasure of seeing them face to face, but obtains access to 

 them by thrusting her long ovipositor into their galleries, having first ascertained, by 

 antennal investigation, that the gallery is tenanted ; but not being in the least particular 

 about the age or sex of her victim. Thus aiming at random, the egg may be depo- 

 sited in the sleek body of a four-year-old, in the slimmer proportions of a three- 

 year-old, or perhaps in the interior of a mere colt, a juvenile that has not yet kept 

 his first birth-day. Now, although the longevity of the Cossus larva is well established, 

 we have no evidence of the longevity of the Ichneumon larva; on the contrary, all the 

 ascertained facts of its history go to prove that its period of existence is uniformly 

 limited to a year; the egg of one year producing a fly the next. Hence, feeding 

 away with the normal voracity of its tribe, the Ichneumon larva exhausts the Cossus 

 larva in a few months, whether it be a one-year, or a four-year-old, always, however, 

 allowing it life enough to form its ordinary cocoon, an operation with which no 

 ichnemonizing seems to interfere ; and hence also we have cocoons of varied sizes 

 proportioned to the age of the Cossus, but quite independent of that of the 

 Ichneumon. I think, therefore, that no doubt need now be entertained on the 

 subject of these familiar little cocoons : and I hope speculative opinions as to their 

 being 'something good' will cease; for of a certainty they are the progeny of 

 veritable 'goats,' and possess the genuine fragrance of their sires, although their 

 existence is terminated by the ungrateful guest they have nurtured while they are yet 

 mere ' kids.' — Edwaed Newman." 



The Secretary observed, in confirmation of Mr. Newman's remarks, he had 

 repeatedly had diminutive cocoons of Cossus ligniperda sent to him for his opinion 

 as to what new species they would produce, and remarked this paper settled a long- 

 standing disputed question. 



