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Keywords:

  • N. lugens;
  • S. furcifera;
  • wing-dimorphism

Abstract. 1. The seasonal changes in abundance of macropterous N. lugens (Stal) and S. furcifera (Horvath) (Homoptera: Delphacidae) are described based on observed numbers of adults and presumptive macroptery in fifth-instar nymphs occurring in rice crops in the Philippines.

2. Percentage presumptive macroptery in fifth-instar nymphs was correlated with nymphal density over the range of 0–20 nymphs per hill for females of both species and 5–20 nymphs per hill for male N. lugens.

3. Lunar phase had no effect on wingmorph expression in either species.

4. Comparison of the percentage macroptery in fifth-instar nymphs with subsequent percentage macroptery in N. lugens adults for one season showed net emigration occurred from 60 DAT (days after transplanting) to harvest except for a period of net immigration lasting 7–10 days at approximately 95 DAT for both sexes.