| Caenis | |
|---|---|
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| |
| Caenis horaria | |
Scientific classification 
| |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Insecta |
| Order: | Ephemeroptera |
| Family: | Caenidae |
| Genus: | Caenis Stephens, 1835 |
Caenis is a genus of mayflies. They are very small in size, sometimes with a body of only an 1/8 of an inch (3.2 mm).