Molecular Entomology, 2025, Vol.16, No.1, 19-27 http://emtoscipublisher.com/index.php/me 24 Among them, the length of the abdominal tube and the width of the head shell of each insect age are significantly different, with a small error range and low overlap, with high identification accuracy, and can be used as a morphological standard for insect age division. This is consistent with the view in Mingxia et al. (2013) and Fu et al. (2022) that the width of the head shell is the main criterion for insect age. 3.3 Observation of morphological characteristics of adults, eggs, pupae, etc. Adult stage: Corn borer adults are medium-sized gray-brown moths, with wingspans of about 30 mm and 25 mm for males and females, respectively. The female moth has yellow forewings with purple-brown wavy patterns, while the male moth is slightly darker and smaller. Adults are mostly active at night, and their lifespan is generally 5~7 days. Mating usually takes place on the second night after emergence. After mating, male moths often become weak and die the next day, while female moths can survive and die after laying eggs. On the corn seedlings provided in the cage, female moths mostly lay egg masses on the back of corn leaves near the midrib, and each female lays an average of about 120 eggs. Eggs: Milky white, flat and oval, arranged closely like fish scales, and the top of the egg turns black before hatching, which is the "black head stage". After the eggs hatch for about 4~5 days, the new generation of larvae crawl out of the egg mass and begin to feed on the tender parts of the host plant. Pupa: Mature larvae pupate in the gaps between corn cob husks or in paper rolls provided by humans. The initial pupa is light yellow and turns reddish brown after a few hours. The pupa is about 15~18 mm long, spindle-shaped, and has no cocoon. The pupal period is about 7~9 days at 26 ℃. The difference between male and female in the pupal period can be distinguished by the morphology of the end of the abdomen: the female pupa has a pair of tail spines at the end, while the male pupa has no obvious tail spines but a round reproductive protrusion. It was observed that males often emerge about 0.5~1 day earlier than females. Multiple generations of observation showed that the morphology was stable and no deformation was found. The pupal body color was typed, suggesting that it may be related to pupal age or sexual development, which needs further verification (Figure 6) (Cagáňet al., 2012; Lu, 2014). Figure 6 Morphological characteristics of Asian corn borer adults, eggs, and pupae Note: A: Adults; B: Bot eggs; C: Black-headed Asian corn borer eggs; D: Mature larvae of Asian corn borer; E: Tubers on the back of the abdomen of Asian corn borer; F: Length of Asian corn borer pupae; G: Asian corn borers of different colors; H: Classification of Asian corn borer pupae of various colors
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