How Big Are Aquatic Insect Adults ? 
How long do aquatic insects live?

Courses Home Knots Equipment Fly Reels Fly Lines Leaders Fly Rods Insectology Flies Fish Casting Reference library Course map   Course subjects What are "insects"? Simply insects Keeping insects simple Basic insect ID Insect life cycles Comparing stages Where insects live Aquatic environment Insect adaptations Mayflies Caddisflies Dragon/Damselflies Stoneflies Terrestrials Stream order Lentic zone Lotic zone   Insects covered Alderflies Ant Blackfly Caddisflies Caterpillars Crayfish Crickets Damselflies Diving beetle Dobsonflies Dragonflies Fishflies Gnats Grasshoppers Mayflies Midges Mosquitoes Scavenger beetle Scud Shrimp Sowbug Spongillaflies Springtails Stoneflies Water bugs Water beetles Water penny Whirlagig beetle  

    The chart below gives a visual representation of the relative sizes of the several aquatic insect adults that are important in fly fishing.  The table indicates the longest a member of the insect family would be expected to be found.  To "translate" the lengths shown in millimeters into inches, conversion is one millimeter equals .0394 inches . . . or, a millimeter is roughly .04 or 4% of an inch.

These are insect adult forms . . . for larval forms, go to the Insect Larva Size chart.  For a side-by-side comparison, see Relative Size Chart.