I will be presenting at Schlow Library (State College, PA) on Saturday as a featured speaker at BookfestPA. This year's BookfestPA is focused on nature, science, and imagination. I'll be giving a 45-minute workshop for kids on animals, and I'll be signing books afterward. Please stop in for this celebration of books and authors, part of the Central Pennsylvania Festival of the Arts. I hope to see you there!

America's favorite butterfly visited my garden today. This Fourth of July beauty sipped nectar from the milkweed and graciously agreed to rest on the peas, giving me a chance to photograph her.

What a thrill to see her! Monarch populations have crashed in recent years due to loss of habitat. Monarchs need plenty of milkweed, their host plants on which they lay eggs. Milkweed once sprouted on farm fields, but thanks to the widespread planting of herbicide-resistant crops—and the resulting overuse of milkweed-killing herbicides—milkweed has nearly disappeared. No milkweed, no Monarchs.

One way to help reverse the damage is to plant lots of milkweed—along roadways, in parks, in back yards. I've got a patch near the vegetable garden, and I'm keeping my fingers crossed my visitor laid a few eggs before moving on.

By the way, how do I know the butterfly is a female? The difference is pretty easy to spot. Males have a black spot on each hind wing. Females do not. Females also have thicker black veins than males. In the picture below, you can see my visitor's thick veins, and you can just barely see that she has no spot on the hind wing.

Compare this with the thinner veins and two black spots on the hind wings of the male in the photo below.

Plants can detect and respond to sounds. But why would plants need to hear? Perhaps to help them fight off hungry insects.

To learn more about how plants respond to noise, scientists played a recording of the munching of caterpillars for one set of plants. Another set of plants was exposed to silence. Later, actual caterpillars chomped on both sets of plants. The difference? The plants that had "heard" the sounds made more anti-caterpillar chemicals than plants that had experienced only silence.

How do plants hear if they don't—excepting corn—have ears? Researchers think that touch-sensitive cells in the plant sense the sound vibrations.

Koalas, those eucalyptus–munching mammals from Australia, are known to drape themselves over tree branches. There is even a scientific term for this behavior: tree hugging. Until recently, scientists didn't know why koalas hugged trees.

Now a team of Australian and American scientists has discovered that koalas are more likely to hug trees on hot days. Infrared photos reveal that the furry marsupials keep cool by snuggling up with a water-filled branch. In hot weather koalas prefer acacia trees, which are noticeably cooler than their usual eucalyptus trees.

Click to see infrared photos and read more about the study.

Lab mice run on exercise wheels. But is that normal behavior for a mouse? To find out, scientists placed an exercise wheel outdoors with motion detector and video cameras. Wild mice were caught on camera as they hopped on the wheel and ran.

Why would wild mice run on a wheel? Probably because it's fun.