Dragons in the Sky

eastern pondhawk. photo by Jo Smith

Dragonflies zip above my hayfield, stitching together pieces of the sky. They’re busy, hunting down gnats and mosquitoes, but every now and then one stops for a moment, perching on a seedy head of grass or a flower.

Hunting gnats is tough – how does one see those tiny pesky things while flying 20 to 38 miles an hour? The key for dragonflies is their compound eyes. Each eye is made up of as many as 30,000 six-sided facets. Those eyes can detect motion as far as 65 feet away. Watch out mosquitoes!

The other neat thing about dragonflies is their wings. Dragonflies can fly backwards, hover, and even loop-the-loop. Like bees and butterflies, dragonflies have four wings. But unlike bees and butterflies, dragonflies can move their front wings independent of their hind wings. It’s like four-wheel drive, but with wings.

A few years ago some scientists tethered dragonflies in a wind tunnel and took photos of their wings in flight. They discovered that dragonflies twist their wings on the down stroke, creating an airflow that generates enough lift to keep 15 – 20 times their weight in flight. Wouldn’t it be cool if aircraft could do that? You can bet some engineers are already on that.

Spend some time watching dragonflies this summer. You can help scientists learn more by becoming a "citizen scientist" for Dragonfly Pond Watch.


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Tuesday's View

Spittlebug-ology

Ever notice foamy white spitballs clinging to some of the tall grass and plants in the “less-mowed” section of your yard? It’s a spittlebug, a baby “froghopper” that’s making that froth.

Spittlebugs are true bugs, like aphids and other sap-sucking homoptera that stick their short pointy beaks into stems. But spittlebugs are messy eaters. As they spill sap down their bodies, they add some air and make bubbles. It makes sense: they don’t have hard shells to protect themselves. And the bubbles help keep their skin moist. Besides, who wants to eat a blob of spit?

To see a spittlebug up close, grab a watercolor brush and a handlens. Then head out to the nearest weed patch – or pine tree – and look for the tell-tale blobs of foam. Use the paintbrush to gently brush the spit aside. In there somewhere you should find a tiny green insect with huge eyes and even huger hind legs.

Spittlebugs can churn out 80 spit bubbles in a minute. Want to watch? Using your paintbrush, remove a spittlebug from its home and put it somewhere else on the plant. Then watch. It might take a few minutes for the tiny guy to find the “perfect” place to tap, but when it does, it will start to make foam. Use a watch to time how long it takes to completely cover itself.

Some other spittlebug questions to investigate:

• Do spittlebugs share foam homes with their friends?
• Where do they tend to hang out: on the sides of stems or where leaves meet the stems?
• Do they build spit shelters in or under flowers?
• How high up on plants do they go?

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