342 THE KNTOMOLOGIST. 



Ichneumon thai smells like a he-goat. These small cocoons 

 occur in the ordinary galleries of the goat-moth, sometimes 

 in oak, commonly in elm, more couunonly in willow, always 

 very near the outer bark, always compact, tough, plentifully 

 provided with silk, and abundantly intermixed with car- 

 penter's chips. 



I have said these small cocoons invariably produce 

 Ichneumons, and always of the same species. Does it then 

 follow that vvhen the larva of the goat-moth is stung by an 

 Ichneumon, it always becomes dwarfed, and, dwindling to 

 the dimensions 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 Ichneu- 

 mons, giving no indication of having contained a parasite 

 until the said parasite emerges and perambulates the tree- 

 trunk, quivering his antennae and rustling his iridescent 

 wings. The mystery admits of another solution. We have 

 seen that the larva of Cossus is of long life : it is also of slow 

 growth. Now, these insect Methuselahs never come face to 

 face with their enemy the Lampronota ; but this lady obtains 

 access to them by thrusting her ovipositor into one of their 

 galleries, having first ascertained by antennal investigation 

 that the gallery contains an inmate. Thus ain)ing at random, 

 the egg may perchance be deposited in the body of a sleek 

 four-year old, in the slimmer body of a three-year old, or 

 perhaps in the interior of a mere colt, a juvenile that has not 

 yet celebrated a first birthday. Certain though it be that 

 the goat-moth larva lives for several years, we have no 

 evidence of the longevity of the Ichneumon larva ; on the 

 contrary, all the evidence yet collected, all the hitherto 

 ascertained facts of its life-history, go to limit its span of life 

 to a single year; the egg of one year producing a fly the 

 next. Hence, feeding away with the normal voracity of its 

 kind, the Ichneumon larva exhausts the Cossus larva in a 

 few weeks or at most months, whether it be one year old or 

 foiu*, always, however, allowing it life enough to form its 

 ordinary cocoon, an operation with which no amount of 

 ichneumonizing ever seems to interfere ; and hence also we 

 have cocoons of various size proportioned to the age of the 

 Cossus, but quite independent of that of the Ichneumon. 

 I think, therelbrc, that no doubt need now be entertained on 



