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(Dec- 9 Ww j 
74 LIFE-HISTORIES OF GELECHIADE 
The young larva bores into the tissue of a tobacco leaf, usually near the 
place where it has emerged from the egg, in cases where the egg was laid on a 
leaf, and mines into the leaf. If the egg was laid on a stem, the young larva 
bores directly into the stem. The mine in the leaf is not large as the larva, 
as soon as it comes across a vein, bores into that until it reaches the midrib 
of the leaf, leaving a trail of black pellets of excrement behind it. The larva 
may take about a week to reach the midrib, the time depending on the distance 
it has to travel. In the case of young plants with hardly any stem the larva 
may remain in the midrib and pupate there ; but, when there is a stem, the 
larva bores into that through the midrib. In either case, whether in midrib. 
or stem, the feeding of the larva produces a gall-like swelling which is a charac- 
teristic sign of attack. This swelling is not immediately evident but appears 
two or three weeks (in the cold weather) after the larva has reached the midrib. 
More than one larva may be present in one stem and thus slitting of the stems, 
as sometimes practised, does not ensure removal of all the larve. 
Pupation takes place in the larval tunnel in the stem or midrib. Prior 
to pupation the larva prepares a hole of exit for the moth, the mouth of the 
hole being covered with a thin white silken webbing. The larva next prepares 
a thin brownish silken cocoon lining the tunnel and pupates in this. The 
pupa is about 6 to 7 mm. long, cylindrical, tapering posteriorly, brown, anal 
segment with small grey cremastral hooks. The empty pupa-case remains 
inside the cocoon. 
The moth is active only at night and passes the day. resting motionless 
on the plants or any suitable object. The moths live in confinement for six | 
to twelve days. 
The following table shows the life-cycle during the winter but in the warm 
weather the period is much shortened :— 



Eggs laid Eggs hatched Larve pupated Moth’s emergence ar 
6—XII 20-XIT 9-II 9-IIT | 93 
6—-XII 20-XII 4—IIT 31-1 115 
8—XII 21-XII 3-II 5-III | 87 
10-XII 23-XII 2-III 20-IIT 100 
18-XII 6-I a 30-III 102 
18-XII 6-I Se 2-IV j; 105 
22—XII 10-I sve 26-11] 94 
22-XII 10-1 oe 5-IV 104 


