Macroinvertebrate guide... Moderate Pollution Sensitivity
| High Sensitivity | Moderate Sensitivity | Low Sensitivity |
Pollution Tolerance ranks
Group 2- Moderate Tolerance
Damsel Fly Nymph - Order Odanata
The damsel fly is a predator nymph with large eyes, 6 thin, hooked legs and 3 oar-shaped tails. These nymphs do not have visible gills.
Crane Fly Larva
The crane fly larva looks like a caterpillar with a segmented body of milky, green, or light brown color and four finger-like lobes at the back end.
Crayfish - Order Decapoda
The crayfish has 2 large claws, eight legs and resembles a small lobster. They may be brownish in color to a bright red, or shades of pink in between.
Aquatic Sowbug
The sowbug is characterized as having a gray, oblong body with more than 6 legs and long antennae.
Scud
The scud looks like a small shrimp. Its body is higher than it is wide and the animal usually has more than 6 legs.
Clams - Class Bivalvia
A clam, is a clam, is a clam. Freshwater clams are often small, about the size of a penny. Half-shells, remnants, are very common in active water.
Net-spinning Caddisfly Larva
These larva cling to the undersides of rocks in riffle areas and extend nets of silken-like thread to collect food particles. Net-spinning caddis flies rarely build cases on the rocks.
Fishfly Larva - Order Megaloptera
The fishfly larva often looks like a small hellgramite (dobsonfly larva) but has a lighter, reddish-tan color or yellow streaks. Fishflies do not have gill tufts as hellgramites do.
Alderfly Larva - Order Megaloptera
Alderfly larva are about an inch long, with one thin, branched tail at the end. There are no hooks or gill tufts in the alderfly.
Beetle Larva - Order Coleoptera
The final group includes pollution tolerant organisms having low pollution sensitivity.
| High Sensitivity | Moderate Sensitivity | Low Sensitivity |
For general information and descriptions of macro invertebrates view or download What are Macros?
Identification and classification manuals are available. For a listing of various sources please go to Resources.