Watt. — Study of New Zealand Entomology. 253 



feature to be recorded is the difference between the sexes, which is to be 

 found for the first time in larvae during the fifth instar. At this period in 

 their life-history certain larvae (the males) have tubercles i and ii coalesced 

 in the 2nd thoracic segment, while all the tubercles excepting i in the 9th 

 and those on the -suranal plate in the 10th abdominal segment are black, 

 slightly enlarged, and most conspicuous. There is also a form very similar 

 to this, the onlv difference being that tubercles i and ii in the mesothorax 

 are not coalesced ; these larvae appear, however, to be only a variety of the 

 female form. In the next, the 6th, stadium it is far more difficult to dis- 

 tinguish the sexes. It appears that the tubercles i and ii in the mesothorax 

 separate again, the only difference between the male and female larvae 

 being that in the male all the tubercles of the thoracic segments are black, 

 whereas in the female tubercles i, iv, and v are white in the mesothorax. 

 There is room for much more work and observation here. 



Imago. — -Meyrick records a variety in which the golden-white discal 

 spots are wholly absent. This variety appears to be extremely rare. The 

 European species, according to Meyrick, differs very slightly from our 

 species in having the hindwings yellowish anteriority. 



Habits. 



Larva. — The young larva emerges at the micropylar end of the ovum, 

 and generally makes its first meal off the empty shell. During the first 

 day its movements are sluggish ; later it becomes fairly active, but during 

 the latter stadiums is again very sluggish. Throughout its larval existence 

 it feeds on the underside of the leaves of its food plant, and stretches at 

 full length, the ventral prolegs clasping the stem or midrib of the leaf on 

 which it is feeding. The presence of larvae is plainly betrayed by the large 

 irregular holes eaten in the leaves of whatever food plants they may be on. 

 During the last few seasons the larvae of this moth have evidenced a decided 

 taste for cultivated flower-plants, and in the case of dahlias and asters have 

 acquired the habit of eating right into the heart of the expanding buds ; 

 in this way many flowers in full bloom hold a large fat caterpillar, which has 

 absolutely ruined the flower from a marketable point of view. Strange to 

 say, only a very close inspection of the flowers will reveal the true state of 

 affairs, since the larva eats into them from below. It is during the first three 

 stadiums only that the young caterpillars utilize a silken thread for de- 

 scending from one leaf to another, and as a means of returning to the food 

 plant when forced to drop from harm's way. The methods of defence 

 differ somewhat according to age : during the primary stadiums the larva 

 will at once drop to the ground on being disturbed, but as it grows older 

 will content itself with throwing the fore part of the body sharply from side 

 to side, even making striking movements with the head at the object dis- 

 turbing it ; if forced to drop, it will rapidly curl and uncurl itself with a 

 flicking motion during its drop, and on striking the ground will hurriedly 

 make off to hide among the leaves and rubbish, or, on the other hand, it 

 may roll itself into a ball and remain motionless. Of course, its green colour, 

 its markings and shape, and its habit of remaining on the underside of the 

 leaves, and also of remaining, while eating, stretched out, and thus resembling 

 a portion of a branch of the food plant, afford it great natural protection. 

 A day or so previous to moulting the larva will seek a safe position beneath 

 some leaf, and there stretches itself at full length. The prolegs are firmly 

 attached to the cuticle of the leaf, but the true legs take no hold whatever, 

 being held close against the bodv. During the next twenty-four hours 



