#FAM #corn #maize Description Fall armyworm is the name commonly attributed to the larval stage of the moth Spodoptera frugiperda. Other Spodoptera species already found in Australia include the lawn armyworm and the dayfeeding armyworm. The fall armyworm life cycle has an egg stage, 5 to 6 caterpillar (larval) stages, a pupal stage and an adult moth stage. The larval life cycle stages cause widespread damage to crops through feeding. Fall armyworm eggs are usually laid on the under surface of leaves in clustered masses of 100-200, covered with a ‘felt like’ layer of scales (Figure 1). The eggs are pale yellow. Small fall armyworm larvae are usually light green to brown, with a dark head capsule. Young larvae feed on one surface of the leaf. What remains is an opaque layer of cuticle referred to as a ‘window’ which are typically more evident than the presence of larvae (Figure 2). Large fall armyworm larvae grow to 3-4 cm, becoming darker as they mature, with pale white stripes along the length of the body (Figure 3). The large caterpillars have a pale inverted “Y” shape between the eyes. Two dark spots with dark spines occur on each body segment on the upper body surface, with 4 black spots arranged in a square on the last abdominal segment. Fall armyworm larvae normally pupate in the soil. The pupae are shiny brown and between 1.3 and 1.7 cm long. Adult fall armyworm moths measure 3-4 cm from wingtip to wingtip. Female moths are slightly larger than males, although both sexes have a white hindwing with a dark-brown margin. Male moths are more patterned and have distinct triangular white spots at the tip and near the centre of each forewing Life cycle Fall armyworm can complete its life cycle within 23-27 days (from egg laying to the emergence of adult moths), when suitable temperatures and host plants are present. The eggs hatch within 2-4 days after being laid on the lower leaf surfaces. After hatching, fall armyworm larvae complete 5 to 6 growth stages within 14-22 days of hatching to reach maturity. Once mature, larvae drop to the ground, where they pupate for around 8-9 days in warmer months and 20-30 days in cooler areas. Female moths lay most of their eggs within 4-5 days of mating, but can continue laying for up to 2 weeks. As fall armyworm does not diapause (suspend development) during the pupal stage, populations are unlikely to establish in areas where temperatures fall below 9-12⁰C and where frosts occur.