Spotted stem borer larvae bore into the stems of graminae after an initial 5-6 days of feeding on young leaves. The larvae bore inside the stalks and inflorescences which causes stalk break down, stunting, malformation and delayed maturity of the host. In instances where crops and climatic conditions are right the larvae can cause yield reductions of up to 75 % (Polaszek 1998, Kranz et al 1977, Sallam & Allsopp 2002). In rice, low tillering compared to high tillering varieties, have less opportunity to compensate for ‘dead hearts’. The formation of ‘dead hearts’ is the result of the borer feeding inside the leaf sheath during the vegetative stage (Rahman et al, 2004).
Larva see Polaszek 1998 for setal map.
Adult ocellus well developed; face distinctly conical with distinct corneous point; ventral ridge slight; labial palpus 3 ♂ to 3.5 ♀ times as long as diameter of eye; forewing length 7-17mm, R1 free, ground colour varying from yellow to brown variable dusted with fuscous scales, subterminal line a light brown line, median line ill-defined, discal dot present, metallic scales absent; hindwing dirty white to grey.Genitalia ♂ costa with median, strong, tapering projection; juxta plate symmetrical with large central part projected caudad, base with 2 notches; arms stout, not extending beyond costa of valva and each with strong sub apical tooth; aedeagus with bulbose basal projection and ventral arm.
♀ ostial pouch very heavily sclerotized; lightly longitudinally wrinkled; well demarcated from ductus bursae; deeply notched caudally; signum lamellate with a median ridge (Bleszynski 1970).
Images will be updated as fresh adult specimens are sourced.Coming soon - PBT link with DNA barcoding for Chilo partellus