40 Recognition characters of some of the commoner 
Single distinctive characters 
1. Forms in which the immature stages (commonly known as nymphs) 
and are plainly visible upon the back. 
Common NAME ORDER Form TAILS 
Stone-flies Plecoptera depressed 2, long 
May-flies Ephemerida elongate, variable 3, long: (rarely 2) 
Damsel-flies Odonata slender, tapering rear-| sce gills 
ward 
Dragon-flies Odonata stout, variable very short, spinelike 
Water-bugs Hemiptera short, stout, very like| variable 
adults 
2. Forms in w 
internally and not 
hich the immature stages differ very greatly from the adults 
visible from the outside, and having the legs shorter, rudi- 
ComMMon NAME OrDER Lecs GILLS 
Water-moths Lepidoptera 3 airs of minute] of numerous soft white 
jointed legs followed] filaments, or entirely 
by a number of pairs} wanting 
of fleshy prolegs 
Caddis-worms Trichoptera 3 pairs rather long variable or wanting 
Orl-flies Neuroptera 3 pairs shorter 7 pees of long, lateral 
laments 
Dobsons Neuroptera 3 pairs tufted at base of lateral 
filaments, or want- 
ing 
Water-beetles Coleoptera 3 pairs usually wanting 
True flies Diptera wanting usually only a bunch 
of retractile anal gills 
3. Further characters of some common dipterous larvae. 
These are distin- 
Common NAME FamiLy Heap TAIL 
Crane-flies Tipulidae retracted and invisible] a respiratory disc bord- 
ered with fleshy ap- 
pendages 
Net-veined midges Blepharoceridae tapering into body wanting 
Mosquitoes Culicidae free with swimming fin of 
fringed hairs 
Black-flies Simuliidae free with caudal ventral 
attachment disk 
True midges Chironomidae free tufts of hairs 
Soldier-flies Stratiomyiidae small, free floating hairs 
Horse-flies Tabanidae acutely tapering tapering body 
Snipe-flies Leptidae tapering, retractile — ee | short taper- 
ing 
Syrphus-flies Syrphidae minute extensile process as 
ae long as the body 
Muscid flies Muscoidea rudimentary truncated 
