Illustrations of common aquatic snail egg masses in Wisconsin (NOTE: egg masses can vary in length/width/diameter based on snail size and species; however, general egg-mass morphology is consistent within the listed genera.

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1)  Raised, elongate gelatinous masses.  Often found  on stones, sticks, stems and leaves in the water.  Variable eggs/mass but ranging between ~30-130 eggs/mass..........Lymnaea/Stagnicola

2.  Relatively flat, elongate egg masses.  Often found on the undersides of rocky substrates ~5-40 eggs/mass.......Bithynia

3) Large, glairy masses; globular in appearance oftentimes laid with overlapping ends giving the mass and almost ovoid appearance.  Occur on stones, sticks, logs and aquatic plants ~ 30-200 eggs/mass.............Physa/Physella

4)  Flat, ovoid egg masses, oftentimes yellowish in color.  Typically laid on vegetation ~20-40 eggs/mass..........Planorbella/Helisoma