June 2013. Bhutan has recently had an outbreak of armyworm. Maize and paddy (in nursery) from 16 of 20 districts were damaged. There was early onset of warm weather after winter, and wet weather followed, which may have attributed to the outbreak. The armyworm resembles Mythimna separata. Can anyone confirm it?

It was said to look like Mythimna (Pseudaletia) separata, but there are a number of species of Pseudaletia and only by looking at the male genitalia can they be distinguish reliably (until the existing DNA barcode data has been validated). There was an offer to identify the moth, if a few males were sent.

Another member commented:
Yes, looks like Mythimna to me and the parasitoid cocoon mass is certainly a Cotesia cocoon mass. This is a larval parasitoid of noctuid caterpillars and you can see that the primary parasitoid adult wasps have emerged from the cocoons (via the exit hole at the end of the cocoon that has a exit ‘lid’ like a submarine’s manhole exit). Possibly something like C. ruficrus which was introduced into New Zealand from Pakistan and is probably the most successful introduction of a biological control agent into New Zealand. Our armyworm (Mythimna separata) is now a minor pest and we only get a flare-up of caterpillars in localised areas after flooding or very heavy periods of rain (upsets the parasitoid activity somehow).
The parasitoid cocoon mass is certainly a Cotesia cocoon. This is a larval parasitoid of noctuid caterpillars and you can see that the primary parasitoid adult wasps have emerged from the cocoons (via the exit hole at the end of the cocoon that has a exit lid like a submarine's manhole). Possibly, C. ruficrus, which was introduced into New Zealand from Pakistan, and is probably the most successful introduction of a biological control agent into New Zealand. Mythimna separata is now a minor pest and flare-ups of caterpillars only occur in localised areas after flooding or very heavy periods of rain (upsets the parasitoid activity).