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Family Blephariceridae - Net-winged Midges

Net-winged Midge - Agathon comstocki - male Marchflyhead Midge - Bibiocephala grandis Marchflyhead Midge - Bibiocephala grandis Mystery Long-legged hanger - Blepharicera Blepharidceridae - Blepharicera Olympian Fly - Agathon Agathon - Agathon comstocki
Classification
Kingdom Animalia (Animals)
Phylum Arthropoda (Arthropods)
Subphylum Hexapoda (Hexapods)
Class Insecta (Insects)
Order Diptera (Flies)
No Taxon ("Nematocera" (Non-Brachycera))
Infraorder Psychodomorpha
Family Blephariceridae (Net-winged Midges)
Explanation of Names
Blephariceridae Loew 1861
Numbers
40 spp. in 4 genera in our area (all members of Blepharicerinae)(1)(2)(3), ~330 described spp. in ~40 genera of 2 subfamilies worldwide(4); in some NA streams up to 10 spp. are known to co-occur(2)
Size
3-13 mm(5)
Identification
Adults can be easily recognized by the network of numerous delicate cracks and folds in wing membrane, and by distinctive resting position, with the wings held at a moderate angle to the body and the hindlegs angled at the tibiofemoral joint. Larvae distinctive, with adaptations to a life in flowing water, including a cephalothorax (fused head, thorax and first abdominal segment) and six ventral suctorial discs: body appears to consist of only 6-7 segments (each bearing a ventral sucker) separated by deep constrictions. Pupae are oval, with flat, soft ventral face cemented to rocks.(6)
Keys to larvae, pupae & adults in(7)(1)(2)
Range
In our area, mostly western(1), only Blepharicera are widespread(8); globally, represented on all continents except Antarctica, and on several large islands, with high regional endemism; Blepharicerinae occur in both hemispheres, Edwardsininae are restricted to the southern hemisphere(7)
Habitat
Larvae live in clean, cool, well-oxygenated rapid streams (cascades, rapids, waterfalls) attached by ventral suckers to rocks or other smooth hard substrata; prepupal larvae often migrate to specific areas of the rock or stream. Adults usually stay in the riparian zone; Blepharicera are often seen resting on the undersides of leaves of riparian trees, while many Agathon and Philorus spp. prefer to rest on wet overhanging rock faces.(7)(6)(5)
Food
Larvae are highly specialized scrapers, grazing on microscopic growths (=periphyton) and other organic matter on submerged rocks; diatoms appear to be a major component of their diet(9)(10). Females of many species are predators of other insects, esp. soft-bodied ones (mayflies, stoneflies, sometimes other Diptera)(2), caught with specialized hind tarsi. The food of males and nonmandibulate females is unknown, but nectarivory is likely in some species.(7)(6)
Life Cycle
Four larval instars. Adults of most spp., esp. the males, are short-lived. Mating typically occurs soon after emergence and oviposition shortly after copulation. Small clusters of eggs are cemented to wetted or emergent rocks. In some species, the female crawls underwater on submerged rocks to lay eggs.(7)(2)
Remarks
Although often considered rare, densities of immature stages can exceed 1000/m², so in some spots blepharicerids both are the dominant grazers and the most abundant insects.(2) They may be a valuable bioindicator of water quality and sometimes an important food for trout.(11)
Works Cited
1.Flies of the Nearctic Region, Volume II, Part 4: Blephariceridae
C.L. Hogue. 1987. E. Schweizerbart’sche Verlagsbuchhandlung.
2.Revision of the net-winged midges of the genus Blepharicera Macquart (Diptera: Blephariceridae) of eastern North America
G.W. Courtney. 2000. Memoirs of the Entomological Society of Washington 23: 1-99.
3.New species of Blepharicera Macquart (Diptera: Blephariceridae) from eastern North America....
A.J. Jacobson et al. 2011. Systematic Entomology 36: 768-800.
4.Order Diptera Linnaeus, 1758. In: Zhang Z.-Q. (ed.) Animal biodiversity: An outline of higher-level classification...
Pape T., Blagoderov V., Mostovski M.B. 2011. Zootaxa 3148: 222–229.
5.American Insects: A Handbook of the Insects of America North of Mexico
Ross H. Arnett. 2000. CRC Press.
6.Evenhuis N.L. (ed.) Catalog of the Diptera of the Australasian and Oceanian regions (online version)
7.Courtney G.W. (1999-) Blephariceridae
8.Aquatic Insects of North America
R. W. Merritt, K. W. Cummins, M.B. Berg. 2008. Kendall/Hunt.
9.Niche overlap of sympatric Blepharicera (Diptera: Blephariceridae) larvae from the southern Appalachian Mountains
A.J. Alverson, G.W. Courtney, & M.R. Luttenton. 2001. Journal of the North American Benthological Society 20: 564-581.
10.Temporal patterns of diatom ingestion by larval net-winged midges (Diptera: Blephariceridae: Blepharicera)
A.J. Alverson & G.W. Courtney. 2002. Freshwater Biology 47:2087-2097.
11.Net-winged midges (Diptera: Blephariceridae): a food resource for Brook Trout in montane streams
G.W. Courtney & R.M Duffield. 2000. Pan-Pacific Entomologist 76: 87-94.