Lepidoptera, a group of terrestrial insects that constitutes of moths and butterflies. Evolving first at about 300 million year ago, these insects have successfully occupied all possible terrestrial niches.
Life of a moth or butterfly goes through four definite stages, the egg, caterpillar, pupa, and adult. Throughout all of these stages, they show a myriad of diversities, not only in morphology, but also in ecology, behavior and all other aspects.
Recently we have described a strange form of modification on the metathoracic legs of a picture-winged moth (Thyrididae) caterpillar. This species of moth, named as Aglaopus decussata (Moore, 1883) is distributed in India, Thailand, West Malaysia, Sabah, Sarawak, Sumatra, Java, West Papua, Philippines, Taiwan, and Bangladesh. This moth has brownish wings with numerous small dark spots. Like the lion's share of other Lepidopteran species, the life history and ecological aspects of this species were largely unknown. We have described the life history and other ecological aspects of this species for the first time.
Interestingly, we have reported a peculiar modifications on the caterpillars of this species. The caterpillars feed on the leaves of Litsea monopetala (Roxb.) Pers. plants within conical leaf shelters. Each caterpillar, in all instars, bear dark black pouch-like modification on the distal part of the metathoracic legs which is easily recognizable and very prominent. The pouch is variable in size (0.5-1.5 mm) and contains yellowish liquid of unknown type. Because of the modified pouch-like structure, the metathoracic legs resemble the hands of boxers wearing boxing gloves. Several modifications on the caterpillars of this moth family (Thyrididae) has been described by various authors, but this kind of modifications is a new phenomenon for these moths.
The modified legs of caterpillars
The exact function and evolutionary aspects of this modification have not yet been ascertained, but we hypothesize that it may be an adaptation for the caterpillars to live inside leaf shelters, or for defense against predators, or to withstand harsh environmental conditions. But further study is required to reveal the exact truth!
The adult female moth (Aglaopus decussata)
For full information, you can go through our research:
Rayhan et al. 2022. On the Picture-winged Leaf Moths (Lepidoptera: Thyrididae) from Chittagong University Campus, Bangladesh, with a report of a pouch-like structure on the caterpillar metathoracic legs of Aglaopus decussata Moore and notes on its life history. TROP. LEPID. RES. 32(2): 118-126. https://zenodo.org/record/7246242#.Y8RmcXZBzrc
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