THE CANADIAN ENTOMOLOGIST. 3ll 



The sj^ecies is less highly coloured than puj-piiri/ascia, from which 

 its larva separates it, and the slight differences in moth and larva remove 

 it sufficiently from the other ally. 



May 25th to 28th find the young larvae hatching from the hibernated 

 eggs. They enter the stem a few inches above the ground, and work 

 down to the natural enLirgement of the stalk that occurs in all plants, 

 whether infested or not, just below the ground-level. At the same date 

 the plant is attacked above by a Micro, in the petiole of the unrolling 

 frond. Both often choose the same plant, though their combined efforts 

 produce little retardation. A very limited gallery is made hy pterisii, for 

 the plant is inadequate for extended mining, the larva eats less, and is the 

 most lethargic of any known. To the fourth moult the larva shows no 

 individuality, except that it belongs to the group having the white dorsal 

 line alone continuous and unbroken. Stage V : Colour dull wine-red, 

 lines white, dorsal continuous. No accessory tubercle YVa, the true IV 

 low down in the generalized Noctuid position. All tubercles small and 

 ill-defined. Head wider than shield. Stage VI: Head 2. t mm. wide, 

 still narrower than shield, and shield small. Colour is much faded. 

 Tubercles same as before, neither IV nor V on joint ten bear setse. Stage 

 VII : Head 2.4 mm. wide, normal. All lines and colours lost in a soiled 

 translucence. The larva now typifies a primitive, generalized form of that 

 section which has in its early stages the continuous dorsal line, not 

 acquiring any special accessory and protecting tubercle plate at the 

 spiracle on joint ten. Of its allies, purpurifascia has acquired a large 

 plate here, and Harrisii a very minute one. All tubercles weak, though 

 black marked \ normal. Length, 37 mm. Pupation occurs in the last 

 days of July, the plant being deserted, and the moths come forth August 

 2ist to 31st. 



Probably no other species suffers to quite such an extent from regular 

 yearly parasitism. Though it is so common and is represented in most 

 collections, the acquisition of a good series is no easy matter. The plant 

 is obdurate for breed-cage experiments, and maturity in the field finds 

 them stung, and doubly stung. So fierce is this struggle and so numerous 

 are the persecutors that it seems natural selection could never play much 

 importance in any unbroken line ; nor is it seen how such mutants as 

 might arise were able to perpetuate a new character. But even the last 

 few centuries must have surrounded our Lepidoptera with greatly changed 

 conditions, and we are little able to speculate conclusively. 



