| - | Antennae are minute (invisible to unaided eye) |
| - | Gills (when present) are not confined to sides of abdomen |
| - | Free-living or live incases made of sand, gravel, or plant material |
| - | Growth instars: 5 |
| - | Legs and antenna are free, not fused to body |
| - | Antennae are as long as or longer than body |
| - | Front of head has curved mandibles which project forward |
| - | Wings are covered with fine hairs, and held tent-like when at rest |
| - | Antennae are as long or longer than body |
Caddisfly larvae are classified as net spinning, free living, or case building. The netspinners build a retreat incorporating a silken net to capture food, similar to a spider web, only underwater. The freeliving build no shelter. The casebuilders build either a portable or fixed case for their protection. All caddisflies lack tails, which differentiates them from mayflies and stoneflies.
Caddisfly pupae have free trailing antennae and legs, unlike aquatic moth pupae whose antennae and legs are fused to their bodies.
Caddisfly adults have antennae as long or longer than their body, unlike alderfly adults whose antennae are half as long as their bodies. Caddisfly adult wings, which are folded tent-like when at rest, are covered with tiny hairs, unlike aquatic moth adults, whose wings are covered with scales.