115] FAUNA OF BIG VERMILION RIVER—BAKER 17 
It will be noted that the nymph and larval forms of most species appear 
coincident with the degree of sewage pollution. Chironomus and Libellula 
are, seemingly, able to accommodate themselves to the contaminated or 
polluted condition of the water in the neighborhood of St. Joseph. The 
adult beetles, breathers of free air, are not affected directly by these un- 
favorable conditions and occur in great abundance, even in the heavily 
polluted parts of Salt Fork above St. Joseph. The Ephemerids occur for 
the most part far down the stream where the water is at most only con- 
taminated. The Neuroptera and Plecoptera are clean water forms and 
were found only in the Middle Fork which does not carry sewage. These 
are also to be found, probably, in the Big Vermilion below Middle Fork, 
but no attempt was made to discover these animals when that part of the 
stream was examined. 
Taste I, DistrIBuTION or INSECTS 


Old River bed 
St. Joseph 
Bridge below 
St. Joseph 
Bench mark 655 
Mile above iron bridge 
near Sidney 
Tron bridge 
| Middle Fork 
| 
| 
| 
| 
| 

Diptera 
Chironomus decorus Joh., larva.............+- x 
Odonata 
Libellula pulchella Drury, nymph............. x Kil |S ciayesatorai| laters biodor| aeetel aoe 
Coleoptera 
Gyrinus analis'Say, adult... 0.0.2. se0. sees BAe) meek? aa Bacrerces| lanoe de oydal| eters | raptors 
Dineutes assimilis Aubé, adult............... Sneek nae.s lercae | esencn Fe heute | Sl ear 
Cnemidotus 12-punctatus Say, adult...........)....] x a ee bas oretsil baeusas |B poner 
Laccopiilus maculosus: Say, adult. 2... ic. elere |) Xs -cee ccleeaes|---- ees lVmeras 
Copelatus glyphicus Say, adult............... Ree See petie a Gece Broneg a i[hasispate 
Hemiptera 
Coricanymphsiarairac cies ieee see oe ee EES |. Se > end aa Peale tees 
Diptera 
Cricolopus trifasciatus F., larva (?).......... babvallisetsxe Kil areeye Mee [eas ool taneteee 
Ephemerida 
Hexagenia bilineata Say, nymph.............. Ase Micon lacistee ol PR al] brid ae aioe baer 
Heptagenia, nymph................ serene Ponta ecerletra pert lerecerere x 
Trecho pier a Narva sys vee becca scene eee Wo, shel asaterece [lata ateragtllsterspersi | vateyass x 
Odonata 
Ophiogomphus, nymph..................-+- Merci | baayerall ys aerotanss le vetetoyel| byer'stoxs sreteveill by a 
Neuroptera 
Corydalismlarval nein a 4 ccioon.t eens Ee Atalba yall eager ae (i eral See) [eel haat ¢ 
Plecoptera 
Perla nymph tia Peers tela ee Hace oer sent eit ol ooo a eisbailbeeeealiccaste| OX 
Lal 
Lal 










