Contents - LAC Biosafety

244 Insect pests in plantations: case studies
it by inserting the abdominal tip into the bag while remaining in a suspended
position in flight. The fertilized eggs develop synchronously within the female
body cavity. When the eggs are ready for hatching, the body wall ruptures and
the posterior part of the abdomen, which by then has become shrunken, falls
to the ground, permitting the neonate larvae to hang on silken threads and
disperse. Each female produces 110–200 larvae. Dispersal is aided by wind.
The newly hatched larva that lands on a host leaflet immediately starts
constructing a bag around itself and completes the work within an hour. It then
starts feeding on the leaflets. Starting usually from the under-surface of the leaf
blade, the larva consumes the epidermal layer and the mesophyll tissues
containing the chloroplasts, leaving the single layer of epidermis on the other
surface. Generally, feeding is patchy, with some portions of each leaflet left
unfed (Fig. 10.15).
Older larvae usually migrate to the branch stems and often to the main
trunk, and feed on the live surface layers of bark, leaving feeding scars on the
stem (Fig. 10.16). Bark feeding is common when the infestation is heavy. Larvae
resting or feeding on stems, with their conical bags held upright, resemble
Fig. 10.15 Falcataria moluccana leaf showing feeding damage by the bagworm
Pteroma plagiophleps.