AQUATIC INSECTS. 
135 
processes (Berosus). Platypsyllidce are scarcely aquatic save in that 
their host the beaver is so. Heteroceridce are semi-aquatic in mud or 
wet sand in all stages. Parnidce, so far as known, are peripneustic or 
have filamentous branchiae ; the Elmides have three pairs. 
Dascillidw are aquatic and while some have functional spiracles, 
others are said to have exsertile respiratory pouches (Hydrocyphon ); 
a few forms of the Donaciince among Chrysomelidie have aquatic larva 1 , 
the larva being found in the roots of aquatic plants. ( Donacia , Hcemo- 
nia.) We have omitted to mention the abnormal aquatic Carabid found 
extremely rarely in England and Annandale has recently described an 
aquatic weevil from Calcutta (Journ. Asiatic Soc., Bengal, 1906, p. 
197) as well as an aquatic glow-worm larva (loc. cit. 1906, p. 107). 
Few Lepidoptera are aquatic but some are very notably so in this 
country. A single Pyralid genus ( Acentropus ) has an aquatic larva (not 
known in India) ; the Hydrocampince include at least several aquatic 
forms including Nymphula depunctalis Guen and N. fhictuosalis in 
which the larva is set with short respiratory processes. Both these 
are common in India, while Hydrocampa , Paraponyx snd Cataclysla 
are known elsewhere. 
A single abnormal Eupterotid is aquatic, the larva of Palmira Bur- 
mesteri being holopneustic but having a covering of long hairs in which 
air is retained ; it comes to the surface to renew the supply. Of Diptera 
we are still largely ignorant but the Culicidce have aquatic larvae, 
variously modified, as do the Chironomidce. Coreihra is in the larval 
state dependent on tracheal gills ; Culex , Anopheles and others are 
metapneustic, but have tracheal gill processes as well ; in all, the 
pupae are propneustic , the anterior spiracles lying within large trumpets 
which are brought to the surface of the water. Chironomidce include 
the forms with hcemoglohin (Chironomus ) as well as those with tracheal 
gills ; the pupae are propneustic or have tufts of gills. The aquatic 
Ceratopogon larvae appear to have no gills and to breathe through the 
skin. Psychodidce have aquatic or semi-aquatic larvae, living in 
algae and weeds, with four ciliated processes at the hind end forming 
a basin round the spiracles, as well as a functional pair of anterior 
spiracles. Dixidce have metapneustic larvae with tracheal gills, the pupa 
with propneustic trumpets. Aquatic Tipulid larvae are well known 
and are metapneustic, some with a long telescopic tail process 
(Bittacomorpha, Ptychoptera). One at least has long tracheal filaments 
(Phalacrocera replicata). The larvae of Blepharoceridce are known to 
live in torrents and near waterfalls, clinging firmly to rocks. Simuliid 
larvae are found in swiftly running water and have five retractile gills; 
the pupa has a tuft of filaments. Stratiomyidce have some aquatic 
larval forms, the larva metapneustic with an expansible ring of hairs 
that hold an air bubble. 
Tabanidce have metapneustic aquatic larvse, as do the Syrphidce in 
some cases, the latter having in some forms (Eristalis, Helophilus), the 
