Application of Dyar's Law in Indian Predaceous Earwig, Labidura Riparia (Pallas) form Bengalensis (Dohrn) (Dermaptera: Labiduridae)

The surface pterygote earwig, Labidura riparia (Pallas) form bengalensis (Dohrn) was successfully reared to study its biology, host specificity and habits in the laboratory. It is omnivorous but preferred small moribund insects except lepidopterans and dipterans. It was the first record of this insect occasionally damaging potato tubers in temporary field storage and cold storage in Uttar Pradesh. The life history revealed five nymphal stages duration ranging from 49–73 days. The close proximity between the mean, observed and calculated widths of head-capsule and the increase in widths of head-capsules of instars place these five well defined instars as per Dyar's law. In males the average ratio of increase of head-capsule width was 1.519 while in females it was 1.280. The values of widths of head-capsules in successive instars of males was slightly higher than the females.