These photos supplement pages 119-135 of the Guide to Aquatic Invertebrates of the Upper Midwest. Information on the biology of Hydroptilidae can be found on page 129. Hydroptilidae are called micro caddisflies because they are so tiny (2-6mm). All three of their thoracic segments have sclerotized dorsal plates and there are no gills on the abdomen. Hydroptilidae most commonly build cases with sand, algae, silk or detritus, but the shapes vary considerably. The photo below is of just one of many types of cases that Hydroptilidae construct.