[1] The adult moths are comparatively small, with a wingspan of 3–4 cm, and have a characteristic resting posture that conceals the black and orange-yellow hindwings under the greyish-brown forewings.

A recent study revealed the existence of density-dependent colour polyphenism and resistance build-up against invading baculovirus by H. puera larvae.

Every year high-intensity outbreaks of teak defoliator occur immediately after the premonsoon showers in late February or early march in Kerala.

The main parasitoids attacking teak defoliator include the tachinid Palexorisa solennis, a eulophid Sympiesis hyblaeae, the chalicid Brachymeria lasus and the three ichneumonids, Eriborus gardneri, Stictopisthus sp.

The bacteria Enterobacter aerogenes, Bacillus thuringiensis, Pseudomonas aeruginosa and Serratia marcescens are identified as causing mortality to the teak defoliator.

Large-scale deaths of teak defoliator larvae characterized by cessation of feeding, flaccidity and subsequent liquefaction of body tissues have been reported by Stebbing as early as 1903.

During 1985, an investigation of microbial pathogens of H. puera was undertaken in the plantations of Nilambur Forest Divisions of Kerala, India, by KFRI detected several dead insects with the characteristic symptoms as observed by Stebbing.

Microscopic observation of tissues revealed the presence of refractile polyhedral inclusions bodies, which stained blue in Giemsa, measured 0.9–2.4 micrometers in diameter in the scanning electron micrograph taken by Jean Adams at USDA, confirmed its identity as NPV.

The NPVs come under the family of baculoviridae and its virions are enveloped rod shaped nucleocapsids containing circular, supercoiled, double stranded DNA.

The ECVs which are the progenies released into the haemocoel from the midgut cells are more infectious than the PIBs and mediate disease spread within the insect body.

Even in the fully mature larvae, HpNPV can kill in 60–72 hours, making it one of the fastest acting insect viruses.