THE POTATO MOTH. 
The Potato Moth : an Experimental Investigation into 
the Methods of Controlling its Ravages in Stored 
Tubers. By F. Stovvard, D.Sc. (Birm.).* 
ABSTRACT. 
(Read May 13th, 1913.) 
One of the most troublesome insect pests apparently present 
wherever potato culture forms a branch of agricultural industry 
in regions where the prevailing conditions of climate are warm 
and dry during the period of crop growth is the potato moth 
(. Phthorimea operculella Zell). This is notably the case in Cali- 
tornia, South Africa, India, and the different States of the 
Australian Commonwealth. The exceedingly mild and equable 
conditions which normally mark the late spring and summer of 
Western Australia are distinctly favorable to the prevalence 
and activities of the pest. 
The active agent of infestation is the larva of the moth, 
which is not only capable of ravaging and causing the almost 
complete destruction of the growing plant, but also of the stored 
tuber. Great difficulty is therefore experienced during seasons 
when the pest is present in large numbers and the season is a 
dry one in preserving against its ravages stored tubers destined 
to be used as “ seed.” Infestation of the crop tuber may occur 
under certain conditions in situ even prior to the lifting of the 
crop, not as has sometimes been stated by the larva penetrating 
the stem of the ravaged plant and thus entering the tuber, but 
through actual exposure of the tuber to infestation as a result 
of insufficient or untimely earthing up, or the occurrence of 
cracks in rapidly drying, stiff soils through lack of adequate 
cultivation. Another common method by which infestation of 
tubers takes place and usually immediately after the lifting of 
the crop is either from exposure in the field or from the practice 
of covering these with haulms on which the moth is present 
as a means of protecting the tubers from the sun's heat. Under 
whichever of these circumstances infestation occurs, and whether 
it commences in the tuber attached to the growing plant, im- 
mediately after the digging of the crop, or in the storehouse, the 
chain of events is practically the same : the eggs of the moth 
are deposited, chiefly in the “ eyes ” of the tuber, these eggs 
hatch in from four to six days, according to conditions, and the 
young larvae, which at this stage are minute objects, make 
their appearance. These at once attack and destroy the tender 
buds which collectively constitute the " eye " of the tuber. 
(Fig. 1.) The infested tuber is thus at an earlv stage rendered 
useless for seeding purposes. The later stages of the attack not 
Botanist ant Plant Pathologist to the Department of Agriculture. 
