
———_- E = 
ee = —— 
a 
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318 XVII.—THE TINEIDAE. 
owing to the insect’s subalpine habitat, any successful 
investigation of its habits, was a matter of considerable 
difficulty. 
The full-grown larva is about 1 inch in length, eylin- 
drical, spindle-shaped, its greatest diameter at the third 
abdominal segment, thence much attenuated towards either 
end. To the naked eye it is apparently without legs, these 
being very small, and it is very sluggish in its movements 
when exposed. The segments are shallowly incised, except- 
ing the seventh and cighth abdominals. Spiracles small, 
brown, circular. Head small, flattened, light brown. Gen- 
eral body-colour transparent shiny white. Tubercles and 
setae minute and very inconspicuous. The larva through- 
out its whole life mines within the bulb of the plant below 
the ground-surface. The duration of the larval existence 
is unknown, though from the length of the mines and age 
of the leaves containing them one may conclude that the 
larval stage occupies two, if not more, seasons. 
Commencing in the region of the tip of the leaf, the gal- 
lery, at first about 4 mm. in width, gradually assumes its mark- 
edly zigzag character, proceeding downwards between the mid- 
rib and the outer margin of the leaf; it never crosses the for- 
mer barrier. As the mine descends, the angles of the zigzag in- 
crease in size. All mining is carried on in the bulb of the plant 
at or just below the surface of the ground; and as the leaves 
grow the gallery is stretched and elongated, and mostly loses 
resemblance to a typical mine, since the extremely thin outer 
cuticle is torn and in most places lost, excepting in the most 
recent portion of the gallery. The zigzag formation of the mine 
is necessitated by the situation of the larva in the bulb, and 
its extent is dependent on the rate of leaf-growth: during fast 
growth the successive angles will be large, while slow growth 
will cause the transverse portions of the gallery to be almost 
parallel to one another. Occasionally one will find a length of 
mine fairly straight for an inch or so, parallel to the long axis 
of the leaf and most usually close against the midrib; the rea- 
son for this may be found on careful search of this portion of 
the gallery—a cast skin adhering to the wall shows that a moult 
has taken place here, and while the larva was laying up for the 
purpose the leaf grew sufficiently to allow it later to mine nor- 
mally parallel to the long axis till again arrested in the bulb 
and forced once more to zigzag. 
Frequently in old leaves the mines may be found to ter- 
minate abruptly, or several inches may be missing; examination 
of the plant will reveal the continuation of the mine, or the 
missing portion, on some other leaf, and further examination 
will show that both leaves, at the time of the change, had been 
in close apposition to one another in the bulb, the larva having 
mined from one into the other, and perhaps later back again. 
One may find not a mine, but only a very faint and slight im- 
pression of one, on the surface of an otherwise sound leaf; this 
is due to the pressure caused by the larva mining in the leaf 
next against it while in the bulb. Never more than one larva 
will be found to be mining in one half of a leaf, but both halves 
of the same leaf may be mined by separate larvae. In such 
cases there is, as one would expect, a direct parallelism in the 
course of the mines. 
The mine is usually on the underside of the leaf, and is 
there very conspicuous; when appearing on the upper surface it 
is, as a rule, not so marked. The colour varies, with age, from 
green to dark brown. 
In the next to last larval stadium the larva, practically 
mature, ceases mining (the gallery is now some 3-4 mm. wide), 
and, leaving the gallery, forces its way, no longer downwards, 
but straight up for about 14-2 in., till just below where the two 
contiguous leaves begin to separate; here, lying with the head 
uppermost and parallel to the axis of the leaf, it rests awhile; 
its body becomes much distended with clear fluid, and within 
it can be seen the next stadium larva about two-thirds the length 
of the old distended skin. When ready it bites a hole in the 
side of the old skin and emerges from it, the cast skin being 
flattened against the surface of the leaf, to which it may adhere 
for many months. The larva is now in its final stadium, the 
whole of which is occupied in the preparation of the cocoon, and 
lasts eight to fourteen days. Total length of the mine, possibly 
3-4 ft. 
The cocoon is constructed in rather a peculiar way. The 
larva, having moulted as above, between two applied leaves, 
makes a transverse cut of about 3-4 mm. in the outer (under) 
cuticle of the inner leaf, and, working upwards, insinuates itself 
under the cuticle; then, turning, it repeats the performance 
downwards, forming a shallow somewhat elliptical-shaped cav- 
ity between the cuticle and the remainder of the leaf. The 
transverse cut extending across its middle is now repaired with 
silk on the inside, and in the completed cocoon is difficult to 
find. The thin outer cuticle receives a liberal strengthening of 
silk on the inside, but the remainder of the cocoon-cavity re- 
ceives little or none. As the leaf grows in length it carries the 
cocoon up with it, and in a few months it is some little distance 
above the ground, and so offers no difficulty to the emerging 
imago. The exposed cocoon is by no means conspicuous; exter- 
nally, it is usually covered by the cast larval skin. It is shallow, 
elliptical, its ends somewhat pointed and depressed into the leaf; 
its long axis is parallel to that of the leaf; average size about 
15 mm. by 3 mm. Owing to pressure by the larva whilst the 
leaves are still closely applied to one another, the leaf on the 
outside of the cocoon receives a hollow depression. The pupal 
stage lasts six to seven months, from February till mid-August. 
The pupa lies in the cocoon in an upright position, its ven- 
tral surface innermost. Colour at first pale creamy white, be- 
coming later light brown, darker on dorsum, to black with pale 
markings on wings prior to emergence. It is somewhat com- 
pressed dorso-ventrally, the ventral surface being more or less 
keeled or prominent along the mid-line. The shape of the pupa 
is frequently influenced by external pressure caused while the 
cocoon is still in the bulb. 
The original specimens of the perfect insect were cap- 
tured, by Mr. Philpott, late in December. Those reared 
by Mr. Watt emerged in August, and their emergence may 
have been accelerated by the warmth of the lowland 
locality where they were reared. Nevertheless, it is 
extremely probable that, in its natural surroundings, the 
moth normally appears in early spring. As nearly all the 
collecting in subalpine localities has been done after mid- 
summer, this fact would, as stated by Mr. Watt, explain 
the apparent rarity of the insect. That the mined leaves 
are extremely abundant entirely confirms this view. 
Sub-family 9.—ELACHISTIDES, 
Head smooth. Basal joint of antennae with pecten, Labial 
palpi moderate, curved, pointed. Maxillary palpi very short, 
appressed. Fore-wings with vein 1b simple, 6 and 7 stalked, 7 
to costa, 8 out of 7 or absent. Hind-wings lanceolate, 2-4 nearly 
parallel, 5 absent, 6 and 7 stalked. (Plate G., figs. 1, 2, 3 neura- 
tion and head of Elachista archaeonoma. 
Represented in New Zealand by the cosmopolitan 
genus EHlachista, 



























































