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Weekend Science Fun: Ecosystem Under Glass

Building and maintaining a terrarium or an “ecosystem under glass” can be a fun science project.

I.    Choose the habitat you would like to study.

Do you want a natural terrarium? A traditional deciduous hardwood forest terrarium might include mosses, ferns and woodland plants. Other terrarium ideas are tropical rain forest, desert or boggy/swampy with carnivorous plants. Research the soil types, plant species you will need, amount of water to provide and what type of sunlight the plants will need. For example, a terrarium that represents the rain forest floor will need a lot less sunlight than one that represents the upper canopy.

Younger children may enjoy a less complicated project, such as simply a few dandelions and some grass from the yard.

II. Gather:
1.    Clear container of plastic or glass
a.    Examples: a food container, such as a large plastic bin that prepared lettuce comes in, a plastic pet habitat, or an aquarium
b.    Tops are optional, but helpful. You will need plastic wrap if you don’t have a top.

2.    Pebbles
3.    Soil, selected to match habitat
4.    Plants – either native or houseplants that are small enough to fit your habitat
5.    Items to add visual interest, such as twigs, rocks, seashells…
6.    Gardening trowel or old spoon (digging implement)

III. Basic instructions
1.    Layer the pebbles in the bottom of the container, roughly one inch deep.

aquarium

This is a garage sale aquarium.

terrarium

2. Add soil until the container is roughly one third full. Create dips, mounds and valleys to add visual interest.

3. Decide on which side of the container will be the front. Plant the taller plants towards the back, smaller, low growing plants towards the front.

terrarium

4. Water thoroughly, taking into consideration the type of habitat you have prepared.

5. Cover the terrarium. Use plastic wrap and a string or large rubber band to hold it on if you don’t have a cover.

Watch as condensation forms on the sides of the container during certain times of the day. You can even see droplets form on the top and “rain” down. A terrarium can be used to study the water cycle.

Once your plants are established, you may consider adding soil creatures. The soil creatures can add an element of interest, but also require more care. Also keep in mind that many soil creatures are active at night.

If you try earthworms, make sure you have the right kind of earthworm. The red wigglers used in worm bins live in leaf litter at the surface of the soil in nature. They do better in bin than a terrarium unless you provide leaves for them.

garden snail

Slugs and snails eat plants. They will both require extra food, such as vegetable scraps, and snails need a calcium source like a clean eggshell. Rolypolies or sow bugs do well in a terrarium, but also need added food. Carrots are good for rolypolies. If you add creatures, be sure to keep the terrarium clean. Vegetables can harbor small mites and/or springtails as well as become moldy.

A well-maintained terrarium may be an interesting science project. Study how fast the plants grow and which types survive best under the conditions provided. If you can keep the mosses happy, you will be able to see the different reproductive structures such as the sporangium and gametophyte. Mosses are non-vascular plants so they must absorb water directly from the soil. They do not have true roots or leaves. Spend time observing different types of mosses and learning about them.

Carnivorous plants require very special care but are also fascinating.

pitcher plant

These are pitcher plants. Insects fall into the “pitcher” and can’t crawl out again.

Hope you give a terrarium a try.

Bug of the Week: Spider Mite Predators

In a previous post about hollyhock visitors, I mentioned the plants had spider mites. I wondered when the spider mite predators would show up. Turns out I didn’t have long to wait.

Spider mites are barely visible with the naked eye, and many of the beneficial insects and arachnids that feed on them are also incredibly tiny. In fact, I wished I had a microscope instead of a camera this week. Let’s take a “look.”

spider mite destroyer beetle

Those grayish black circles towards the top are lady beetles, but not the large orange and black ones like you might expect. These are called spider mite destroyers (Stethorus picipes). If you were not looking closely they might look like a bit of dirt or tiny seeds on the plant leaf. I can tell they are lady beetles by their rounded shape.

spider mite destroyer beetle pupa

The lady beetle larvae are on the plant feeding on the spider mites as well, as evidenced by the greyish pupa lying along the middle of the leaf.

You can see more of the life stages at the UC Davis IPM Online site.

red mite

A large red mite like this one might seem to be a bigger version of a problem mite, but it is actually a beneficial predator of spider mites. When you see single red mites that are readily visible and actively crawling about on leaves, that is probably a predatory mite feeding on plant mites or small insects. Mites have round bodies and eight legs.

minute pirate bug

Other point-sized predatory insects on the hollyhocks are minute pirate bugs (Orius tristicolor). (That is “minute” as in small, not the word for time.) The adults are black and white.

Minute pirate bugs feed on a number of small insects and mites. Here are some young pirate bugs or “nymphs” feeding within the webs of the spider mites. The nymphs are orange.

minute pirate bug nymphs

For a better look at the life stages, try this biological control page.

I didn’t get photos, but there were also some predatory thrips eating spider mites. Thrips are often thought of as plant pests, but some species are predatory.

It is great to see all the beneficial organisms having a banquet of spider mites. And I didn’t have to do anything except watch the show.

Weekend Science Fun: Bird Moms (and Dads)

Right in time for Mother’s Day, we have a hummingbird nest filled with two baby hummingbirds outside our upstairs front window. There is a creeping fig vine that climbs over the front door and this is the fifth time hummingbirds have nested on it.

baby hummingbird

Do you think that is the mother bird or a baby? We know from experience that it is a baby because the mother’s beak is much longer relative to her head size. As you can see, the mother bird is a bit messy about the bird droppings.

I’m afraid this isn’t the best photo. The circumstances are less than ideal to take a photo and I didn’t want to disturb the chicks in any way. The nest is incredibly tiny and very hard to spot.

Take a look around your neighborhood and see if you can locate any birds making nests. You might want to take photos and make records of what is happening to the nest over time. Always be sure to respect the birds and stay well out of their way as much as possible.

If you want more opportunities to watch birds, you can put up bird nest boxes. Take a look at Nestwatch for ideas and projects.

If you can’t find a nest to watch, check the Cornell Lab of Ornithology Nest Cams.
If you have a sensitive youngster, be aware that the owls and hawks feed their young animal prey and it shows on some of the cams.

Looking back, we have had quite a few posts about birds. Here are links to a few.
Build a Bird Nest (Human-sized)

Bird Watching and Making Nest Cards

Desert Bird Curriculum Guide

Pigeon Watching

Have fun and let us know what you see.

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