Lepidoptera

Lepidoptera is a species-rich taxa group containing butterflies and moths, but only moth species in subfamily Acentropinae of Crambidae are truly having aquatic larvae and a few species from other families have been reported e.g. Pyraustinae of Crambidae and the family Arctiidae (Mey & Specidel 2008). In Hong Kong, about 20 acentropine species have been found near freshwater marshes and streams. The morphology of aquatic larvae are varied in different habitats and feeding behaviours. Some larvae may or might not have gills living in standing or slow moving water to feed on floating plants. Some other larvae have gills living in moderate fast flowing streams to construct silken nets on rocks for feeding algae.

Note: Subfamily Nymphulinae (Family Pyralidae) has been changed to Acentropinae.

Key to aquatic larvae of acentropine genera in Hong Kong (excluding terrestrial species - Nymphicula)

	Features for ID	Scientific name
1	Larvae without gill
	---> hook rows equally sized; hook row on abdominal segment X (S10) straight or slightly curved	Elophila sp.
	---> hook rows unequally sized; hook row on S10 strongly curved	Cataclysta sp. *
1	Larvae with gills	2
2	Body dorsoventrally flattened, head prognathous, gills unbranched
	---> Body greatly dorsoventrally flattened, gills may arise from cupola laterally	Eoophyla sp.
	---> Body slightly dorsoventrally flattened, gills may arise in groups, likely 3 on abdominal segments	Strepsinoma sp. **
2	Body cylindrical, head hypogathous or semi-prognathous (in oblique angle)	3
3	Larvae without branched gills, head hypogathous, living in fixed nest
	---> Mature larvae with 2 rows of loose gills on thorax and abdomen	Paracymoriza sp.
	---> Mature larvae with 3 rows of dense gills on thorax and abdomen	Eristena sp.
3	Larvae with branched gills, head semi-prognathous or hypogathous, living in portable case
		Parapoynx sp.
	Larval species not yet described	Agassiziella sp.

* In Hong Kong, there is only Cataclysta angulata under genus Cataclysta recorded. The features listed in table are applied to Cataclysta lemnatan for reference.
** Only Strepsinoma croesusalis under genus Strepsinoma was recorded in Hong Kong.

 

References:

Chen F, Song S & Wu C-S. (2003) A review of the genus Paracymoriza Warren in China (Lepidoptera: Crambidae: Acentropinae). Aquatic Insects: International Journal of Freshwater Entomology. 29:4, 263-283

Habeck D-H. (1996) Australian moths for Hydrilla control under Aquatic Plant Control Research Program. Technical Report A: 96-10.

Vallenduuk H-J, Cuppen M-J. (2004) The aquatic living caterpillars (Lepidoptera: Pyraloidea: Crambidae) of Central Europe. A key to the larvae and autecology. Lauterbornia 49: 1-17.

Wolfram M & Speidel W. (2007) Global diversity of butterflies (Lepidotera) in freshwater. Hydrobiologia 595:521–528.

Yen S-H. (2012) Insecta: Lepidoptera, Crambidae, Acentropinae. Freshwater Invertebrates of the Malaysian Region: 545-554.