Nallachius americanus (McLachlan)
Introduction
This week’s insect is rarely encountered and belongs to a small family of neuropterans, the pleasing lacewings (Dilaridae). Dilaridae contains 101 species worldwide (10 genera), distributed in all regions except Australasia (Oswald, LDL). Of the two species in the US, only one is found in NC. Individuals will come to lights and resemble small moths (their wingspan being about 1cm), but can be told apart by their many wing veins (especially the multiple subcostal veins) and mandibulate mouth parts. The family’s position within Neuroptera is uncertain, having traditionally been placed near Berothidae and Mantispidae, but now with unknown affinities (Winterton et al., 2010).
Taxonomic History
The family’s type genus, Dilar, was named for a river in southern Spain. McLachlan described this species as Dilar americana in 1881. It was later transferred to the genus Nallachius (thus Nallachius americanus) by Navas in 1909 (Carpenter, 1947).
Diagnosis
Nallachius americanus is the only species of pleasing lacewing found in North Carolina, and the only other species in the US (Nallachius pulchellus) is found in Arizona. Pleasing lacewings differ from other NC neuropterans in a number of ways including the highly pectinate male antennae (seen in the pictures) and a long, up-curved female ovipositor (Gurney, 1947). In life, adult males rest with their wings spread (see top picture). Larvae are long and thin with pointed mouth parts (see bottom picture; Gurney, 1947).
Natural History
Adult females are attracted to the larval habitat, specifically dead, standing trees or rotting logs and stumps. Females lay eggs in or under the bark using their long ovipositor. The larvae develop under the bark, living in the space between the bark and wood or in the galleries of other wood inhabiting insects. Like most other Neuroptera they are predatory, using venom delivered through syringe-like mouth parts formed by the mandibles and maxillae (drawings in Gurney, 1947). They have been observed to feed on wood-boring beetle larvae (e.g., Cerambycidae) and probably feed on any soft-bodied arthropod they can capture. Apparently they can only slowly pierce the prey through head movements, so fast or highly-mobile prey may be difficult to consume. Larvae are unusual, at least among neuropteran larvae, in that they appear to undergo a variable number of molts, from 2-12, sometimes without feeding (though this was mainly observed in the laboratory). Also, the old skin splits around the insect between the pronotum and mesonotum, whereas most other larvae have skin that splits down the center (MacLeod and Spiegler, 1961).
Habitat
This species is usually found in deciduous forests with enough decaying wood for the larvae to live in. MacLeod and Spiegler (1961) further describe the type of habitat of Nallachius with reference to typical flora.
Distribution
Nallachius americanus is widely distributed in eastern North America, having been collected from Michigan to Texas, and Washington DC to Florida; they are likely found in other eastern states. The species is also known from the Caribbean. Our two specimens are from North Carolina and Arkansas.
Find out more
- Carpenter, F. M. (1947) Taxonomic notes on the Dilaridae (Neuroptera). Psyche, 54: 100-109.
- Gurney, A. (1947) Notes on Dilaridae and Berothidae, with special reference to the immature stages of the nearctic genera (Neuroptera). Psyche, 54: 145-169.
- MacLeod, E. G. and P. E. Spiegler (1961) Notes on the larval habitat and developmental peculiarities of Nallachius americanus (McLachlan). Proc. Ent. Soc. Wash., 63: 281-286.
- Winterton, S. L., Hardy, N. B. and Wiegmann, B. M. (2010), On wings of lace: phylogeny and Bayesian divergence time estimates of Neuropterida (Insecta) based on morphological and molecular data. Systematic Entomology, 35: 349–378.
- Oswald, J. D. (chief editor). Lacewing Digital Library. http://lacewing.tamu.edu/. Accessed on 15 June 2011. (Nallachius americanus)
- Nallachius americanus on GBIF
- Nallachius americanus on Bugguide
Map
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