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HABITS OF THE INSECT. 
When fully established in a district, both those potatoes which are in the ground | 
and those which have been removed from it and are stored are subject to the attacks 
of the moth. At Toowoomba, as far as we learn, it is only those tubers which have 
been dug up which, as yet, suffer. Mr. G. Searle, in reply to our questions, re- 
marks: 
‘““T am perfectly sure that the insect is not in the potato while this is in the ground. 
We are almost daily using potatoes which were all dug at one time, immediately 
picked up, and placed in a dry-goods cask in which straw was placed between each 
layer of tubers. The cask is covered up by a corn bag, and, with the exception of a 
few near the top of it, none are affected by the moth.” In Tasmania it was ‘‘in- 
variably found that the moth attacks the roots. The uppermost potatoes, those 
which are nearest the surface, are of course most easily reached, nor is it by any 
means a difficult matter for the insect to penetrate to the depth of three or four inches 
when the soil is open, uncompressed, or lumpy. Not a single case of an infected stalk - 
has yet been detected, but constant and numberless have been the instances in which, 
when uncovering the noteboes at the depth just indicated, moths have been cislogege 
and flown uninjured away.” 
Of course some of these, however, as must have occurred to the author of these ob- 
servations, might have hatched from pupe still in the ground; but in anticipation 
of this objection he adds: 
‘“The potatoes, whilst lying exposed in rows, were attacked by the insects *~ * * 
and it was always noted that the moths, when unengaged in laying eggs, were al- 
most always to be found beneath the clods of earth with which the ground was en- 
cumbered.” 
Otto Tepper remarks: 
‘“My opinion is that the eggs are first deposited by the moths under the stalk near 
the ground, when the infant grub burrows through the soil till reaching the tubers; 
or the moth itself burrows, as many are found to do, and deposits the eggs direct 
upon the tubers. My reason for this is the fact that the longer the tubers are left in 
tke soil the more infected they will prove to be.” 
Boisduval’s observations, too, though somewhat different as to detail, support this. 
view as to the mode in which the moths find access to the tuber, whilst the latter is. 
sti]l beneath the surface of the ground. : 
What is the nature of the operations which take place beneath the surface of the 
ground may be concluded from what was noticed in our breeding apparatus. The 
moths had no partiality for perfectly sound tubers, but would attack those which 
had previously afforded sustenance to a generation of their kind. In asound potato 
the eggs were laid several side by side in contiguity to an ‘‘eye” of the tuber; in a dis- 
eased one, on the earth-covered surface of a cocoon, within the hole previously exca- 
vated by acaterpillar which had emerged for the purpose of pupating, or amongst the 
‘“‘frass” surrounding the entrance to this cavity. As many as twenty-six eggs, laid 
by a single moth, were in one instance counted in the same location. The eggs hatch 
in a week or ten days, and often more quickly. 
The young caterpillars immediately proceed to burrow into the tuber, at first con- 
cealing themselves beneath numerous particles of rejected food material fastened 
together with web, the number of which particles is being continually increased by 
similar matter brought to the surface. The channel thus formed is also lined with 
web, so that when the substance of the tuber is broken down these burrows appear 
as hollow tubular bodies. The caterpillars arrive at their full size in from two to 
three weeks + and then find their way to the surface of the potato and burrow out- 
“We, however, bred a specimen of the insect from a potato leaf sent by Mr.G. 
Searle. This the caterpillar had folded up. 
t Tepper makes the minimum to be forty-five days. 
hE a ae Ns alan 
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