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During this feeding period, larvae thrives on dry grain diet. At 28'C, larval stage lasts around 1-1.5 weeks before they start spinning web into cocoon and become pupae.
Sexing Plodia Larvae
Male Plodia larvae can be distinguished from its female counterpart by the presence of two dorsal red dots indicating their testicular mass.
Pupal stage lasts for about 1-1.5 week at 30'C. At the end of wandering larval stage, larvae will spin silk around themselves. Once their pupal case is hardened enough, it is safe to open the cocoon and take out the pupa inside. They can then be lined up on a double-sided tape that has been dabbed with a kimwipe to reduce stickiness. Pupal staging is based on their body, eye, tarsal claw, and wing color progression from cream, tan, to dark brown. Zimowska et al (1991) described in detail how to stage the pupae through observable outer structure and how those stages relate to the ovary maturity.
Sexing Plodia pupae is performed under dissection microscope. In females, the abdominal segments on the ventral side near their genitalia are shaped distinctively (dotted lines) from males. Males also have a pair of rounded sex marker near their genitalia. In addition, the distance between anus and genitalia in male is generally shorter than in female pupae.
Sexing Plodia Adults
Apart from the morphological differences illustrated above, male and female Plodia also show difference in pre-mating behaviors. Females will bend their abdomen upwards to call males for mating using their pheromones. As a response, males will flap their wings to court the nearby female.