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Washington State University

Water Bugs – Explorer: Skill Level One

Water Bugs

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EXPLORER – Skill Level: One

Looking at Bugs
Aquatic Sampling

Activity: What’s swimming in your stream?

Objective: Discover biodiversity by observing freshwater insects and other macro invertebrates.
Science Skills: Observation
Life Skill: Communicating, record keeping

Preparation Activities:
• Collecting and looking at resource books
• Make an Observation Log
• Making a Kick Net (see Stream Assessment Guide)

What You Will Need:
Nets, kick net, white bottomed dish pans, magnifying glasses, rulers, pads, pencils, sample jars, squeezable sports bottle, turkey-baster and/or eye dropper.

Check “It’s All Connected” for a list of publicly accessible streams known to currently support freshwater insects and other macro invertebrates.

1. Plan a day to visit one of these locations.

2. Read over and discuss Safety and Ground Rules with youth before your exploration.

3. Fill out observation logs:

a. Describe the Habitat: Observe the water. Is it clear or cloudy, cold or not so cold, moving fast or barely moving at all? If you have a photographer, photograph your location.

b. Natural defenses: ask the youth to make guesses about where the bugs might be, how do they use their environment to protect themselves?

4. Fill a white dishpan or similarly sized container with some of the stream water. Also fill a squeezable sports bottle with some stream water.

5. Follow the collecting and sampling instructions in the Stream Assessment Guide.

6. Have each youth select a different aquatic insect, and continue diagrams and observations in their observation logs.

a. Method/Speed of Movement: How do they move around the dishpan ? If you add some small rocks or sticks to the dishpan do they cling to them? Many insects cling tightly to the rocks in the fast moving water. Notice their body shapes. How would their body shapes help them live their lives? Are their bodies still or do some of the insects move their bodies in place?

b. Food/ Method of Ingestion : All aquatic macro invertebrates need to absorb the oxygen that is dissolved in the water.

7. Offer resources to help them identify and name their insects and macro invertebrates.

a. Aquatic Insect and macro invertebrate key –

b. Freshwater Macroinvertebrates from Streams in Western Washington and Western Oregon –

c. Hafele, Rick, Scott Roederer, and Richard Bunse. An Angler’s Guide to Aquatic Insects and their Imitations for all North America. Rev. ed. Boulder, 1995. Print.


– macro-invertebrate
– fresh water
– scrapers
– shredders
– predators
– herbivores
– food web
– biodiversity

Teachable Moments:
Some insects need a lot of oxygen and can only survive in very healthy streams with little pollution and lots of oxygen. Others can thrive in relatively polluted conditions. Scientists study samples of aquatic insects like the one’s you’ve collected to learn about the overall health of a stream.


Many aquatic insects have gills on their bodies. For example, most mayfly nymphs have visible gills on their abdomen (the part that looks like its tail), and they sweep their abdomens from side to side to absorb more oxygen from the water.


Stonefly nymphs have bushy gills where their legs attach to their bodies, stoneflies will bob their bodies up and down (as if they were doing push-ups) to absorb more oxygen.