order
                        
                      
                                    Coleoptera
                                       “Adult Beetles”
                                  
                                    Coleoptera
                                       “Larval Beetles”
                                  
                                    Diptera
                                       “True Flies”
                                  
                                    Ephemeroptera
                                       “Mayflies”
                                  
                                    Hemiptera
                                       “True Bugs”
                                  
                                    Lepidoptera
                                       “Aquatic Caterpillars, Snout Moths”
                                  
                                    Megaloptera
                                       “Alderflies, Dobsonflies, and Fishflies”
                                  
                                    Odonata
                                       “Dragonflies and Damselflies”
                                  
                                    Plecoptera
                                       “Stoneflies”
                                  
                                    Trichoptera
                                       “Caddisflies”
                                 family
                        
                     Caenidae
               
            genus
                     Caenis
            
                  “Small Square-gilled Mayflies”
               
      Genus Overview
                  
               
                        Larvae of the 12 North American species of this genus prefer slow-moving or stagnant water where there is an abundance of silt, and loose sediment, and are often found sprawled on/in the silt or climbing among the plants. They feed by collecting and gathering tiny bits of organic matter or by scraping algae and biofilm from rocks and other substrates in their habitat. The adults and subimagos of this group are short-lived and hatch (molt into adults) in large numbers. They are imitated by fly fishermen; however, you must time your fishing trip just right or you will miss the "hatch." In addition, during the hatch, fish often feed almost exclusively on these insects, so fly-fishermen without matching tied-flies, are not likely to be successful.
                  
               Characteristics
                  
               POLLUTION TOLERANCE
                        Southeast: 7.6 and higher
                                 Upper Midwest: 7 and higher
                                 Midwest: 3.1 and higher
                                 Mid-Atlantic: 7 and higher
                              0 = least tolerant, 10 = most tolerant
                        FEEDING HABITS
                        
                                 Collector / Gatherer
Scraper / Grazer
                        
                     Scraper / Grazer
MOVEMENT
                        
                                 Climber
Sprawler
                        
                     Sprawler
DISTRIBUTION
                        
                                 Widespread (east of the Rocky Mtns.)
                        
                     HABITAT
                        
                                 Lentic-littoral
Lotic-depositional
                        
                     Lotic-depositional
Diagnostic Characters
               order
                         
                                       
                                       
                                    Abdominal Gills
                                  
                                       
                                       
                                    Single Tarsal Claw
                                  
                                       
                                       
                                    Usually 3 Tails
                                 family
                         
                                       
                                       
                                    Square Semioperculate Gills
                                 genus
                         
                                       
                                       
                                    Eggs
                                  
                                       
                                       
                                    Operculate Gill with fringe of long hairs
                                  
                                       
                                       
                                    Stout spines on protibia and protarsus
                                 
                  + Expanded Character List
                  
                     
               
            
                        Order:
                           Wings developing in wing pads. Mouthparts suitable for chewing. Gills present on tops and sides of abdomen. Segmented legs present. One tarsal claw per leg. Usually with 3 tails (sometimes 2).
                     
                     
                        Family:
                           Mesonotum without anterolateral lobes of Neoephemeridae. Hind wing pads absent. Paired gills on abdominal segment 2 nearly square, and meeting or almost meeting medially (but NOT fused), at least partially covering succeeding pairs (semi-operculate). Plate-like gills on abdominal segments 3–6 with fringed borders. Mature larvae 2–8 mm long, not including tails.
                     
                     
                        Genus:
                           Maxillary and labial palps three-segmented. Segments 2 and 3 of labial palps about same length or 3 shorter than 2, with few long setae and spines. Ocelli without neighboring tubercles. All legs subequal in length. Foretibiae and tarsi each with row of stout spines along inner margin. Outer margins of operculate gills fringed with long setae.  Note: Several eggs can be seen looking at the ventral of thorax and abdomen in the given picture.
                     
                   
                   
            Dorsal
               Ventral
               


