CANAIHAN KN'IDMdI.iHllST. 17 



journey of some twelve inches in length, and there it foinid and closed 

 another leaf". This made three ca.ses by this one small larva. The day 

 after it look possessioii of the third case, I foimd it dead, with a cocoon 

 by its side. It would seem as if a premonition of what was to happen 

 impelled these parasitized larviv to make extraordinary preparations for 

 their final resting places, and 1 have constantly observed that an unusual 

 amount of spinning had been done, coating the inside of the case thickly, 

 where dead lar\;\i were found. These cases are closed more carefully 

 than others, so that on inspection it is ditficult to find an aperture which 

 would admit anything. I have seen no other parasite about Atalanta 

 larva.' than the fly. Apatcles i^c/rc/iice. and a single cocoon of this, when 

 found, has always rested b\ the side of a larva of second stage, and no 

 other. 



The c]uestion mav be asked, when does the fiy dejjosit the egg which 

 leads to the destruction of the larva? It is not laid in the egg, for if it 

 was no larva would emerge therefrom. Butterfiy eggs are often stimg by 

 parasite Hies so minute as to be scarcely discernible, and from the egg. a 

 few (lavs later, will issue several similar tiies, each about .02 inch long. I 

 apprehend that our larva is stung by this fly just after it has come front the 

 egg. and before it has made for itself a case, for except at this little interval 

 of time, the leaf is closed. And when a hole is eaten in the side, the 

 netting spoken of would apparently suffice to keep out this particular 

 enemy. In the next stage there is no such close protection, and probably 

 hot much need of it. for I have not found an ^4/'<?/rt'///rt; larva infested at any 

 stage after the second. Accordingly, after the first stage there is nothing 

 to screen the holes made in the case, the nerves being eaten as well as 

 the substance of the leaf, and I have never been able to find a web, or 

 threads extended across the opening. When the whole outer end of the 

 case is devoured, as sometimes happens in second and third stages, there 

 is nothing to prevent any enemy entering. 



The ri\ then stings the larva, most likely at the very beginning of the 

 existence of the latter, deposits in the body a single egg, and from that 

 there is hatched a grub which feeds on the fatty portion of the larval 

 interior, avoiding any vital organ, till at the close of the second larval stage 

 it has devoured nearly all but the mere shell, and is itself then full-grown, 

 and eats its way out of the side of the dying larva. Presently this grul> 

 has encased itself in a cocoon of its own spinning, a white cylinder, .15 

 inch long, and there it lies by the remains of the caterpillar, in the tomb 



