WATER QUALITY: Analytical Procedures - "Permanent Slide Method for Larvae of the Family Chironomidae" by L. J. Tilley and S. S. Hahn 


                                           January 9, 1974

QUALITY OF WATER BRANCH TECHNICAL MEMORANDUM NO. 74.08

Subject: WATER QUALITY: Analytical Procedures - "Permanent 
         Slide Method for Larvae of the Family Chironomidae" 
         by L. J. Tilley and S. S. Hahn

In many aquatic biological studies, it is necessary to 
separate benthic invertebrate samples into different kinds 
(taxa) of organisms. The taxonomic identification of some 
taxa is difficult because characteristic structures are very 
small and because of the vast number of taxa within certain 
groups. These difficulties are perhaps most pronounced with 
the Family Chironomidae.

Chironomidae (commonly called chironomids or midges, 
sometimes called bloodworms) are insects and are one of the 
most abundant and varied of all groups of benthic 
invertebrates. Their general taxonomic classification is as 
follows:

     Phylum:          Arthropoda
     Class:           Insecta
     Order:           Diptera (flies)
     Family:          CHIRONOMIDAE
     Genera (common): Pentaneura, Chironomus,
                      Procladius, Tanypus

The chironomids are of special interest in that, (l) immature 
forms (larvae) have proven to be of great value as indicator 
organisms of water quality and, (2) adults of certain species 
cause nuisance problems in some areas of the United States. 
Chironomids do not bite nor carry disease, but they do emerge 
in tremendous numbers. Adults frequently are attracted to 
lighted areas in waterfront areas where they die, accumulate 
on window sills, and give off a very offensive ordor.

The chironomids have been subjected to many years of 
taxonomic confusion and constitute at present one of the most 
difficult groups of insects with which to work. As with most 
groups of insects, taxonomy of the chironomids is based 
largely on adult characteristics. In addition most of the 
publications concerned with the group are either extremely
regional or out-of-date.

In order to identify chironomid larvae properly, slide mounts 
must generally be prepared.  The attached provisional 
procedure describes in detail the techniques essential for 
mounting chironomid larvae for taxonomic identification.

Questions or comments pertaining to the procedure should be 
directed to the Chief, Quality of Water Branch (Mail Stop 
412, Reston, Virginia).


                                  R. J. Pickering

Attachment

WRD Distribution:  A, FO-LS, PO