Contents - LAC Biosafety

10.8 Falcataria moluccana (Fabaceae: Faboideae) 245
Fig. 10.16 Larvae of the bagworm Pteroma plagiophleps feeding on the live bark of
the branches of the tree Falcataria moluccana. With the bag held upright, the
larvae resemble thorns.
thorns. When reared on F. moluccana saplings in outdoor cages, the larval period
lasted 49–66 days, the females taking longer than the males. Prior to pupation,
the larva attaches the bag, with a thick silk thread, to a twig and closes the
mouth of the bag: the cocoons thus hang on the branches (Fig. 10.17). The male
cocoon is comparatively short, with a truncated posterior end, while the female
cocoon is longer and has a tapering posterior end. The pupal period of the male
is about 14 days. The male moth has atrophied mouthparts and lives for about
four days in laboratory cages. Thus the duration of the total life cycle from egg
to adult is about two to two and a half months.
In Kerala, India, bagworms were present in F. moluccana plantations
throughout the year, and up to five generations per year have been recognized
(Nair and Mathew, 1988). However, over a three-year study period, outbreaks
leading to heavy defoliation occurred only once or twice a year. In one year,
outbreaks occurred in April and June, causing total defoliation in some patches,
but the population collapsed in August, probably due to incidence of a fungal
disease. Outbreak populations were usually of similar age although overlapping
of developmental stages was common at other times.