Contents - LAC Biosafety

10.17 Tectona grandis (Lamiaceae) 349
Fig. 10.44 The adult teak sapling borer Sahyadrassus malabaricus. When at rest,
the moth (wingspan up to 110 mm) hangs in a characteristic posture.
lays thousands of eggs, which are believed to be broadcast while in flight. In the
laboratory, an unmated female laid 4 166 eggs (Nair, 1987b). Early larval instars
have not been observed in the field and it is not known where they live. Although
moth emergence is usually completed by mid-May, it is not until some three
months later, in mid-August, that the new generation of larvae are found on
saplings. During this period, infestation on the saplings builds up suddenly over
a few weeks. By then, the larvae are already 15–20 mm long. Obviously the early
instars survive elsewhere, probably on litter or humus on the ground or on
weedy vegetation, and later migrate to the teak saplings. Larvae of most species
of Hepialidae occupy tunnels excavated in soil and feed on roots or ground
vegetation, but the early instars of some species pass through a litter phase when
they feed on detritus, fungi or fungus-infested wood before moving to living
saplings (Grehan, 1987; Tobi et al., 1993). A litter phase has been recorded in the
related species Endoclita sericeus, while the young larvae of E. signifier are known
to feed on the stems of grasses. A similar feeding habit can be inferred for the
early instars of S. malabaricus.
In the sapling, the larva occupies a tunnel in the centre of the stem, along the
pith (Fig. 10.45). The tunnel mouth is located at a height of 5–60 cm above