New host plant record, first report of natural parasitisation, report of 'parasitoid guarding' behaviour with notes on biology and identification of Thyrassia virescens (Hampson, 1892) (Insecta: Lepidoptera: Zygaenidae)

Caterpillars of Thyrassia virescens (Hampson, 1892) were collected from a newly recorded host plant Cissus quadrangularis Linnaeus, 1767 (Vitaceae) in Chikaballapura district of Karnataka State in India from June to September 2021. Larvae were reared in room condition to study the life cycle. The total larval period was found to be 18-22 days with four instars. The pupal period was found to be 10-12 days. Parasitisation by Cotesia sp. (Braconidae: Hymenoptera) on the caterpillars of T. virescens has been documented for the first time. While there was no parasitisation occurred during the first generation, the second and third generations showed 93.3% and 18.18% parasitisation respectively. Notes on the identification features such as the male and female genitalia have been described. An interesting 'parasitoid-guarding' behaviour has been documented, in which the caterpillars seem to protect the parasitoid cocoon from hyper-parasitoids and other enemies until the emergence of parasitoid adult.