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The complete mitochondrial genome (mitogenome) of Artogeia melete was determined as being composed of 15,140 bp, including 13 protein-coding genes (PCGs), 2 rRNA genes, 22 tRNA genes, and one control region. The gene order of A. melete mitogenome is typical of Lepidoptera and differs from the insect ancestral type in the location of trnM. The A. melete mitogenome has a total of 119 bp of intergenic spacer sequences spread over 10 regions, ranging in sizes between 1 and 48 bp. The nucleotide composition of the A. melete mitogenome is also biased toward A 1 T nucleotides (79.77%), which is higher than that of Ochrogaster lunifer (77.84%), but lower than nine other lepidopterans sequenced. The PCGs have typical mitochondrial start codons, except for cox1, which contains the unusual CGA. The cox1, cox2, nad2, and nad5 genes of the A. melete mitogenome have incomplete stop codons (T). The A. melete A 1 T-rich region contains some conserved structures that are similar to those found in other lepidopteran mitogenomes, including a structure combining the motif ATAGA, a 19-bp poly(T) stretch, a microsatellite (AT)n element, and a 9-bp poly(A) upstream trnM. The A. melete mitogenome contains a duplicated 36-bp repeat element, which consists of a 26- bp core sequence flanked by 10-bp perfectly inverted repeats.

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The pine caterpillar, Dendrolimus punctatus (Walker) (Lepidoptera: Lasiocampidae), is a multivoltine pest of pine trees in China, overwintering as larvae. Winter diapause was induced by short day length. The critical night length was about 10 h 40 min at 25, 28, and 31 °C in the field, showing a temperature‐compensated diapause induction. Transfer experiments from a short night (L16:D8) to a long night (L12:D12) or vice versa at different times after hatching showed that sensitivity to day length was restricted to the first 14 days; the required day number for a 50% response at 25 °C was about 3.5 days for short nights but 7.5 days for long nights, indicating that short nights are photoperiodically more effective. When four successive short nights (L16:D8) were used to interrupt the long‐night regime (L12:D12) at different development stages and vice versa, the results showed that the highest sensitivity to photoperiod occurred on the 4th−8th day, corresponding to the second larval instar. Experiments of alternating short‐night (L16:D8) and long‐night (L12:D12) cycles during the larval period showed that the information of short nights as well as long nights could be accumulated. By rearing the larvae under conditions other than 24‐h light–dark cycles, we clearly showed that the dark period (scotophase) played a major role in the determination of diapause. The Nanda‐Hamner and Bünsow experiments failed to reveal rhythmic fluctuations with a period of about 24 h in the occurrence of diapause. Therefore, the photoperiodic clock in D. punctatus is an hourglass timer or a damped circadian oscillator.