Aquatic Insects Investigation (3rd Grade)
Objectives
1. Use physical characteristics of macroinvertebrates to predict which insect it will grow up to be
2. Identify stages in macroinvertebrate life cycle
Other objectives can include: predicting water quality based on aquatic insects, identifying and
predicting changes in aquatic food webs
Virginia Standards of Learning
3.8b: animal and plant life cycles
3.6a: water-related environments (pond, marshland, swamp, stream, river, and ocean
environments)
3.5: The student will investigate and understand relationships among organisms in aquatic and
terrestrial food chains. Key concepts include
a) producer, consumer, decomposer;
b) herbivore, carnivore, omnivore; and
c) predator and prey.
3.4: The student will investigate and understand that behavioral and physical adaptations allow
animals to respond to life needs. Key concepts include
a) methods of gathering and storing food, finding shelter, defending themselves, and
rearing young; and
b) hibernation, migration, camouflage, mimicry, instinct, and learned behavior.
3.9d: water supply and water conservation
3.10: The student will investigate and understand that natural events and human influences can
affect the survival of species. Key concepts include
a) the interdependency of plants and animals;
b) the effects of human activity on the quality of air, water, and habitat;
c) the effects of fire, flood, disease, and erosion on organisms; and
d) conservation and resource renewal.
Science Content
Aquatic insects (macroinvertebrates) start out life in aquatic habitats and end their life as adults on land.
Some go through complete metamorphosis (egg, larvae, pupa, adult) and some go through incomplete
metamorphosis (egg, nymph, adult). Aquatic insects are used as bioindicators (give evidence of water
quality) because some are more sensitive than others to pollution and habitat degradation. These
insects play many roles in aquatic food webs: primary consumers, detritovores, herbovires, omnivores,
predators, prey. They serve as food for larger organisms both in the water and when they are adults on
land. Because these insects serve so many roles and because some are sensitive to pollution,
conservation of healthy waterways is important for promoting biodiversity of macroinvertebrates which
then support biodiversity in the rest of the community.
Goals Promoted
Students will:
Maintain a high level of curiosity regarding the world around us.
Be creative.
Clearly express scientific insight to others.
Engage in scientific inquiry.
Display a robust understanding of fundamental science content.
Work effectively in groups.
Act responsibly as citizens (globally and locally).
Set goals, make decisions, and accurately self-evaluate.
Think critically.
Solve problems using accurate scientific knowledge.
(Source: Penick & Bonnstetter, 1993)
Materials
-Live or dead macroinvertebrates: a couple different species, with at least one good sample of each
species. Preserved dead macroinvertebrates work well, but they can be fragile. Live ones are more
exciting, but you may not be able to find enough. The UVa-Wise Natural Sciences Dpt. has preserved
insects (in the governor’s School Macroinvertebrate kit and in collection jars in a lab—the ones in the kit
are labeled and separated already)
-White trays to fill with water and put insects in: there are also some of these in the Governor’s School
kit, or you can use ice trays if you want, or a bowl.
-Forceps or anything that kids can use to pick up the insects: also in the Governor’s School kit
-Magnifying glasses or a dissecting microscope: The Wetlands Project has 10 magnifying glasses
-Pictures of adult insects (can use attached pictures)
-Optional: Macroinvertebrate Life Cycle or ID flashcards (The Wetlands has 4 sets available). In place of
this, you can use live macroinvertebrates or just print out pictures of various species…or just talk about
them with no pictures
Set-Up
Arrange desks or tables (or if you’re outside, just put supplies in a group on the ground or on a chair or
something) into groups. Make sure each group has at least 2 people in it (3 works best), but no more
than 4 so it doesn’t get too crowded. Each group should have a tray with a little water in it and a couple
macroinvertebrates of the same species floating around in it. Each group gets a different species to look
at. Each group should also have pictures of adult insects to look at, forceps, and magnifying glasses.
Ideally, each student will have a magnifying glass and forceps, but if there’s no enough you just have to
make sure students all take turns (1 minute of investigating and then rotate tools or something).
Lesson Development
Introduction: 5 minutes
I’ve got two ways to start off this lesson, so think about each one (the advantages and disadvantages in
terms of student thinking), and then you can pick one… or come up with something better! When
students enter the room, have them choose a seat (making sure each group has at least 2 people in it)
and KEEP THEIR HANDS OFF THE TABLE. Tell them you need their full attention so they know what to do,
but assure them that they WILL get to play with the bugs shortly. Possible introductions:
1. Tell the students that what they’re looking at (but not touching yet!) on their tables are aquatic
insects. What do you think that word “aquatic ”means? Maybe throw out some other words
that it sounds like (aquaduct, aquarium, etc). And these are all insects: how do we tell an insect
from other types of bugs? S: Six legs! The other thing you guys need to know is that these insects
are all babies. Each group has a different kind of baby insect. You guys also have pictures of
adult insects at your table. Each baby that you guys are looking at is going to grow up to be one
of the adults that you see. Your job for the next 5 minutes is to use your investigtative skills and
try to figure out together which adult the babies at your table are going to grow up to be. If
students haven’t had much experience making observations and inferences, you can go over
together how they might go about figuring this out. Ask things like: What characteristics might
you look at to try to identify these insects? S: Look at their legs, bodies, color, shape, heads, etc.
How will that help you to figure this out? Maybe they look the same on the baby and the adult,
so you can compare them. Rationale: students can then look for six legs on each bug—they
might think things like a hellgrammite have more, but you can talk about fake legs then. Giving
them this bit of information narrows down the amount of things they have to compare on
babies and adults (though some will still say “I think it’s a mayfly because they both have 6
legs”).
2. Instead of telling kids what they’re looking at right away, just tell them that they’re baby bugs.
Rationale: if you do this, you can then ask them questions about the bugs after their
investigation is over (i.e., What did you notice about the number of legs on all these bugs? If
they had six legs, what can we call them then? These are special insects that we call “aquatic
insects”—what do you think that means? If they live in the water though, how come the adults
that you have pictures of don’t live in the water? That question can then lead into the idea of
lifecycles because students might mention something about that).
Investigation: 10-15 minutes (Exploration phase of Learning Cycle)
Ready, set, go! Start investigating! Give students about 5 minutes to do their investigations of the insect
on their table. As they work, walk around asking questions:
What are you guys observing about your bug?
What do you think it will grow up to be? Why do you think that? Typical answer will be “they’re the
same.” You can then ask elaboration questions: What looks the same on them? What about the legs
makes you think they’re similar? What’s different about them?
What are you guys looking at to try to figure this out?
What makes this hard to do?
Why do you think it won’t grow up to be this one?
What things do you think might be unique about this bug?
Students might have a problem with the babies not having wings. They might think their bug will grow
up to be the water beetle because they both don’t have wings (wings that they can see, at least).
Hmmm, so you think the bugs are born with wings? S: Well, maybe they can grow wings. Other students
in the group might offer that suggestion, too. What else do you think could change by the time they
grow into adults? S: Maybe their color or bodies could change, too.
After students have gotten an idea of which insect they might be looking at, transition into the next part
of the investigation: So, you guys have gotten a chance to try to figure out which adult matches your
baby bug… but I’m going to give you a chance to look at the other bugs in the room so you can be more
confident in your matches. Before we switch tables, I need to you guys to put down all your tools, make
sure all the pictures are on the table, stand up… and move this way to the next table. Take 2 minutes to
investigate this new bug and try to match it to its adult!
Let students have a couple of minutes at the new station, then switch again. Keep switching until they’re
back at their original station, then give them one minute just to refresh their memories about what they
first thought.
Questions to ask:
How does this bug look different than the one you just looked at?
How does seeing this bug change your mind about what the other ones might be?
Discussion: 10-20 minutes (Concept Development stage of Learning Cycle)
After students have had a minute to look at their first bug again, have them put down all the tools and
focus on you again.
Are you guys curious to know the identities of these bugs? S: Yes!! Well, I’m going to tell you… but first I
have some questions for you.
*If you didn’t tell them that these were aquatic insects at first, here’s a good place to go through that.
Here are a couple of options for proceeding with this part of the discussion, too. Feel free to pick one,
mesh them together, or do something completely different!
2. Go around to each group and have them tell the class what they though the bug at their table
was and why they thought that. Make sure they articulate their observations clearly. Then ask:
What made this hard to do? S: they don’t look the same, the babies don’t have wings, etc.
3. Ask the class: What characteristics did you look at to try to identify these bugs? What made this
hard to do?
Then talk together about this question:
How do you think the babies get to look like adults? S: They grow up and change, metamorphosize
OR
What do you think has to happen before the babies look like the adults? S: They grow up, change,
metamorphosize
If students don’t come up with the word “metamorphosis” ask if they have ever heard that word before.
What other animals go through metamorphosis? S: butterflies and frogs!
Where you go from here depends on whether or not the students have already studied life cycles or not.
If they have, you can ask: What did these insects start out as? S: eggs. Then what do they hatch into? S:
larvae. Then what comes next? S: pupa. And finally? S: adult!
If students haven’t studied this yet, you can introduce these stages to them using pictures or something,
drawing on the board maybe…or you can have them act it out! Have them stand up and move a little bit
away from their desk.
The first stage in their lifecycle is an egg: students crouch down on the floor like a ball.
Then they hatch into something we call a larva: students stand up and raise their arms above their
heads (and they can wiggle around like a worm a bit, too!)
Then comes the pupa stage, like when a butterfly forms a chrysalis: students wrap their arms around
themselves… or find some other way to act out pupa
Finally, they hatch into adults: students wave their arms around, flapping them like wings. If they’re not
too wild, you can even fly around together!
Insects like the water beetle (water penny) and the caddisfly go through this complete metamorphosis
(you can then identify these on the tables if you haven’t done that already); but, some of these insects
go through incomplete metamorphosis, with only three stages in their life cycle.
They start out as an egg, like in the complete metamorphosis: students get in position.
Then they hatch out as a nymph: students stand up and put their arms out to their sides, but with their
elbows tucked into their sides, so that only their forearms stick out. They can wave their fingers around
like legs.
Then they morph into an adult: students spread their arms out like wings!
The mayflies, stoneflies, and dragonflies, and dobsonflies go through this incomplete metamorphosis
(you can point these out if you haven’t identified them yet…or wait until the very end of class).
Identifying characteristics you may want to point out:
Dragonfly nymphs: big eyes, fatter body, two really short tails
Mayfly nymphs: 3 tails
Stonefly nymphs: 2 tails and long antennae
Helgramites/Dobsonfly: pinchers
Depending on what else you want to cover in this lesson, you can stop here and do some follow-up
with lifecycles with butterflies or frogs or something, or you can keep going and cover roles in
ecosystems and aquatic habitat conservation.
Roles in Ecosystems: 5-30 minutes
Depending on your goals for this part of the lesson, you can do an in-depth study of food webs, or you
can just mention some of the roles they play. If students are learning these roles for the first time, you
can construct an aquatic food web together as a class, using these insects that they now know. Be
creative in coming up with a way to do this! If you just want to review these roles with them, the
conversation might go a little something like this:
So, we know a little bit about how to identify these insects and about how they go through their
lifecycles... but why else do you think scientists might want to study these creatures? Allow wait time for
students to think and throw out some answers—lead into discussion based on their ideas or ask some
more questions:
What roles do you think the insects play in the food web in the water? S: they get eaten (what can we
call them then? S: prey), they eat things (what things do you think they might eat? why do you think
that?)
Some of these insects eat plants in the water. What do we call an animal that only eats plants? S:
herbivore!
Some of these insects eat plants and animals: what can we call them? S: omnivores! What are some
other examples of omnivores?
The dragonfly nymph is a predator: what does that mean? What do you think could be his prey? Talk
about how these insects are primary consumers and secondary consumers (use the words or not,
depending on what the students know or what you want them to know).
Even though the dragonfly nymph is a predator, it is also prey, just like all the other insects: which
predators in the water do you think eat these insects as prey?
How do you think the fish population would change if there weren’t as many insects living in the stream
all of a sudden?
From this question, you can transition into conserving habitats.
Aquatic Habitat Conservation: 5-30 minutes
For this part, you can use the Macroinvertebrate flashcards or pictures of different insects to show
students which groups of insects are sensitive to pollution and which are not.
Group the pictures or flashcards together according to sensitivity to pollution and have students crowd
around the pictures so that they can all see. It might also work each group to have a set of flashcards so
they can see better.
This group over here doesn’t really mind pollution all that much. And some of them don’t need certain
things for habitat, like rocks or fast moving water, either.
Identify each insect, and you can review lifecycles, too.
Here’s a black fly larvae and mosquito larvae: how similar do they look to the adult black flies and
mosquitoes that we love so much?
Do they go through complete or incomplete metamorphosis? How do you know? (since they have a
larvae stage, they do complete metamorphosis). What stage will come next in their life cycle?
On to the next group, the somewhat sensitive insects:
The insects in this group are sort of sensitive to pollution. They can handle some, but if there’s too much
they won’t be able to live there.
Again, you can identify some of these insects. Ask students which ones they recognize from their
investigation. If they don’t recognize any of them, hold one up and ask which one it is, so they can then
focus on identifying characteristics. Example:
Which insect is this? S: Dragonfly! How do you know it’s a dragonfly? S: it has the big eyes and the tiny
tails in the back. Which stage in his lifecycle is this guy (or girl) in right now? S: Nymph! How is the
lifecycle of a dragonfly different from the lifecycle of a black fly?
Finally to the sensitive group:
This last group of insects is pretty sensitive to pollution. They can handle a tiny bit, but not as much as
the last group.
Again, you can go through and identify some of the insects. Students will get excited when they can
recognize them on their own!
Since all these insects react differently to pollution, we can use them to get an idea of what the water
quality is like in a stream, pond, lake, or wetland.
If we went out and took a sample of aquatic insects from a stream in town, and we only found insects
from the very first group (point to them), what might we be able to conclude about the health of the
stream? S: it’s polluted! And how do we know that? S: the insects that don’t like pollution aren’t there.
What might the aquatic insect population look like in a clean stream? S: they will be insects from the last
group, the sensitive group!
Here students might think that only sensitive insects would be found, but you can remind them that the
other groups can live there, too! You’d probably find lots of different kinds of insects because they can
all live in that clean habitat.
If we think back to our food webs that we talked about, why might it be important to have lots of
different kinds of aquatic insects in a stream? S: There’s more connections in the food web then, and it’s
more stable. The fish and other creatures have more options for food. There are more prey, more
primary consumers.
So, it sounds like having clean water helps to have a healthy food web—a stable community of animals in
the streams, ponds, lakes, or wetlands. We know that not all water is clean, though. What kind of
pollution do you think gets into the water?
From here you can transition into talking about where pollution comes from, how we can prevent it, and
re-emphasize why it’s important to have clean water (not only for these insects, but for us and all the
other animals that depend on it, too!). You can also talk about what makes a good aquatic habitat—
these insects and other animals need more than just water to survive. They need shelter, light, the right
temperatures, nutrients, etc. You can go over the “anatomy of a healthy stream” and talk about having
rocks, branches, and other pieces of shelter and habitat, having shade above the water to keep the
temperature cool enough, having decomposing matter to provide nutrients.
NOTE: Introducing too many new concepts in this lesson will make it not very effective. For an
effective learning cycle, pick one topic to focus on, like life cycles, and carry that through all the way
to the Application phase without introducing other new concepts. If the other concepts are review for
the students, it can be beneficial to talk about them in connection with life cycles, to help them
integrate ideas and make connections; however, avoid throwing too many things at them. I’ve written
up all these ideas in this lesson so that you can pick and choose and use them to spark new ideas.
Please feel free to modify this lesson and expand it and do whatever you think is best to achieve your
learning goals!
Further Application: 20 minutes (or use as homework)
To complete the Learning Cycle with the life cycle concept, you need to have students review the idea
and use it in a new way. For an easy review, you could have them fill out a worksheet with pictures of
different life cycle stages. Here are some ideas:
-Put the stages of each life cycle in order, and label them (pictures of a few different organisms, of
complete and incomplete metamorphosis)
-Have flashcards of life cycle stages of a couple of organisms, pass them out to each group, and have a
race to put them in order. The first group to get done, raises their hand, but before they can get the
prize (or applause, or bragging rights, or something), they have to name each stage and say whether it’s
complete or incomplete metamorphosis.
After review, students can apply their new knowledge of life cycles in a new way. Here are some ideas:
-Write a story about the life of one of these insects they learned about today. This can tie in with SOL’s
from English class! Maybe you could combine vocabulary from English and this lesson and have them
write a story using all the vocabulary words. This could even tie into art SOL’s, if they are learning about
sketching, using colors, using perspectives, etc. They can write and illustrate a story or make it into a
poster or something.
-How would our lives be different if we went through life cycles? Maybe you can have each group come
up with a 5 minute play or demonstration about what their life would be like if they had to go through
metamorphosis. Ex: maybe right now they would be in the larvae stage, but graduating from 3rd grade
means it’s time for pupa stage. So, they would have to be eating a lot, like a caterpillar, and instead of
playing baseball or soccer or going to camp this summer, they would be in their pupa stage. When they
hatch into adult stage right before the start of 4th grade, they would be real adults: done growing!
-If you do this lesson at the right time of year, you can take the class out to a stream and actually spend
some time collecting aquatic insects! Kids love getting to do this, since many of them probably never
would have noticed that the insects were there! You can get supplies from UVa-Wise or the Lonesome
Pine Soil and Water Conservation District. Spend about 30 minutes or so collecting insects, them take
some time to identify them. You can even maybe have half the class get aquatic insects, while the other
half catches adult insects with bug nets. Then they can compare babies and adults, look for similar and
different traits, and review life cycle stages.
Collecting aquatic insects can also be done to help reinforce the habitat conservation ideas, because
they can see what kind of habitat is in the stream, and can rate the stream quality based on which
insects they find. For further application of this concept, if you can’t get out in the stream, you can give
them a worksheet that is a picture of a stream, with different types of habitats and pollution problems,
and they can identify everything and predict what kind of insects might live there. Give a couple
different streams in different conditions, so they can decide which one will be polluted, which one will
be clean. The other part of the worksheet can be predicted stream quality based on insects caught. Give
some examples, and have students say whether the stream is clean or not. For even more application,
you can build a healthy stream as a class. Give each student a “piece” of a stream: rocks, trees, insects,
fish, and they can place them on the board to make a stream. You can then introduce pollutants (i.e.,
put a farm upstream) and ask how that will affect the stream and what they could do to keep the
pollutants out of the stream.
Dragonfly
Stonefly
Caddisfly
Dobsonfly
Water Beetle
Mayfly
Name:____________________
________
Label the stages of the mosquito life cycle.
1.
Is this complete or incomplete metamorphosis?
__________________________
4.
How is the lifecycle of a mosquito similar to the
lifecycle of a butterfly?
2.
How is it different than a butterfly?
3.
http://www.biotechpestcontrols.com/assets/images/mosq_1_.jpe
g
Draw and label the stages of a dragonfly life cycle. The
dragonfly goes through incomplete metamorphosis.
Stage 1: ____________
On the back of this page:
Draw or write a story about how
your life would be different if
you went through complete or
incomplete metamorphosis.
How would you start life? Which
stage might you be in now? How
would your daily life be different
if you were in that stage rather
than just being a kid? What stage
would come next? What would
be different about your life if you
lived half of it under water?
Be creative!
Stage 2: ____________
Stage 3: ____________