Spatial dynamics of teak defoliator (Hyblaea puera Cramer) - Cochin ...

insect lays eggs only on a single day and the presence of instars other than the
dominating one was due to the difference in developmental time ofthe insect. The
present study shows that egg-laying on different days can also lead to the
presence of more than one instar. This oviposition behaviour need not necessarily
be typical as the present observations were made during the month of July in a
young plantation. More observations are needed on the oviposition behaviour of
the immigrant moths during the early outbreak period.
Based on the results of this study, the sequence of events from the
emergence ofmoths to the start ofthe next outbreak can be described as follows:
The newly emerged moths after a period of about one hour move by active
flight to form an aggregation. Moths that have emerged from different stands
and/or those emerged on different days form part of the same aggregation. After
mating, the aggregation moves to a new habitat. Post migratory aggregation can
also bring in moths from different stands or those emerged on different days. Both
males and females will be part of this group but females are predominant. It
seems that the aggregation remains until the completion ofegg-laying.
The behaviour of the defoliator moths proposed above can explain many
of the characteristics ofH. puera population dynamics. Incidence of outbreaks in
different patches at the same time can be caused by short-range movement of a
group of moths during the period of egg-laying. Similarly, the simultaneous
occurrence of more than one stage of the insect at any particular stand can be
explained by the fact that the insect lays eggs on the same stand more than once.
It is not certain whether the eggs laid on a single stand on different days is by the
same group ofmoths or by different groups. Long-range movement oflarge group
of moths outside teak plantations observed in this study could cause sudden
outbreaks in plantations.
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