232 THE CANADIAN ENTOMOLOGIST. 



quarters for the change. In this case an exit aperture for the moth must 

 be made and the provisional instinct here called forth is certainly a 

 departure from the usual preparatory action taken by larvge. The ample 

 orifice through the plant-stock and the lid at the epidermis to screen 

 against intruders are good examples indeed of insect forethought. That 

 cerussata and marginidetis do not undergo their changes in conditions 

 which bring out such a display of instinct would hardly place them on a 

 lower plane, and we may look for a cause from some other source, being 

 anxious to find an excuse for these beauties. 



Having a habitat that extends further southward than the other local 

 species gives them a longer season, so that on becoming full-fed there 

 may seem less haste for the change to a chrysalis, and they might indulge 

 in a little roaming. After once leaving their burrows, we cannot expect 

 them to find their way back again, so refuge is sought in mother earth. 



Upon encountering the larva of cerzcssata, it is easy to see at once that 

 we have to deal with a species differing greatly from the conventional 

 form. The head is larger, the plates stronger and the tubercles seem more 

 clustered, together with a parchment-like cuticle^ giving the insect quite 

 an armoured appearance. And it is needed ! The food-plant is Vernonia 

 noveboraceiisis, and if anyone doubts the aptness of the common name 

 " ironweed " as applied to this plant, it would be well for them to 

 investigate the roots, for it is here the borer works. It would be well to 

 take some heavier tool than a penknife or garden trowel when undertaking 

 the task. 



Larvee in next to the last stage were found July 15. The plants had 

 been entered a few inches up from the base and a gallery started downward 

 into the roots. Progress was slow on account of the extreme toughness 

 of the stem. A very noticeable swelling is produced, but instead of 

 increasing in diameter as the plant continues to grow, finally bursts open 

 for its entire length, making an ugly scar, at once furnishing a clue for the 

 hunter. From this time on that part of the burrow offers no shelter 

 whatever and the workings below ground proceed slowly. Often the 

 borer misses the centre of the stem, for be it known there is no pith to 

 guide it, and eats its way through to the outside. Then the gallery is 

 continued through the soil and tangle of fiberous rootlets ; but this does 

 not occur until near maturity. 



Next to last stage ; Very cylindrical, the skin more roughened and 



