22 September 2020

Pretty soon it’ll be too cold for frogs but right now we still have a chance to see these two in Pennsylvania. Though similar it’s useful to know the difference because one is mildly poisonous.

Northern leopard frogs (Lithobates pipiens), at left above, are harmless and sometimes green. Don’t rely on their green color for identification though because some are plain brown. All four below are northern leopard frogs from the same place in Minnesota. Notice that the spots on their backs are irregular circles and somewhat scattered even on the brown one.

Pickerel frogs (Lithobates palustris) are mildly poisonous. When frightened they excrete a poison from their skin that’s toxic to predators and mildly irritating to human skin. To identify them, notice the chocolate brown blob-like rectangles arranged in two rows between the two folds on their backs (dorsolateral folds).

The Pickerel frogs can also be distinguished by the bright yellow or yellow-orange color on the inside concealed surface of the thigh. Leopard frogs are white in the same area. 

— BioKids article at Univ of Michigan

Here’s a live pickerel frog showing off his spots.

The Pickerel Frog shows off its striking pattern. If it’s cover gets blown, plan B is the poison that it packs in it’s skin. Mildly irritating to people, distasteful to predators, they are the only native poisonous frog in the USA. pic.twitter.com/GN2HdltcKc

— incidental naturalist (@IncNaturalist) September 15, 2020

He’s the one that’s poisonous.

p.s. A note on Poisonous versus Venomous:

• Poison is passive, just used as a defense. You have to ingest or touch a poisonous substance to be harmed by it.
• Venom is active, injected into you by the animal that carries it. It’s used as both offense to capture prey and defense.

(photos from Wikimedia Commons, click on the images to see the originals)

10 September 2020

Though 2020 has been an awful year it has a silver lining: Monarch butterflies are relatively plentiful. I saw my first monarch in late July. Now that they’re migrating to Mexico I see several every day.

How are they navigating to Mexico?

During their fall migration, Eastern North American monarch butterflies (Danaus plexippus) use a time-compensated sun compass to aid navigation to their overwintering grounds in central Mexico.

— Antennal circadian clocks in migratory monarch butterflies

The compasses are in their antennae! Combined with a circadian clock that figures out where the sun ought be at any time of day, the compass compensates for the sun’s position and keeps the monarch heading in a southwesterly direction.

Monarchs can navigate better than some of us!

On Throw Back Thursday, read more in this vintage article: The Sun Compass.

(photo by Steve Gosser)

p.s. The article was written seven years ago when the monarch population hit a dangerous record low. The population rebounded in 2018-2019 but it’s hard to know if they’re safe yet. This population graph from Journey North was not updated in spring 2020. I’ll bet COVID-19 interfered.

5 September 2020

This week saw flurries of warblers migrating through Pennsylvania and a lot of bug love. The bugs were easy to photograph at Moraine State Park on 31 August.

Above, two insects are frozen in place as they mate on a boneset flower. I don’t know who they are. Do you?

Below, we were astonished to see large reddish galls on staghorn sumac leaves. These are woolly aphids called Melaphis rhois, one of the few whose eggs cause galls.

According to Wikipedia:

The galls occur when female aphids lay a single egg on the underside of the sumac leaf, inducing the leaf to form a sac over the egg.

There are so many galls on this sumac that they look like fruit.

It’s also called “red pouch gall.”

My friend Melissa bravely opened a gall which scattered white powder everywhere. Woolly aphids!

Inside the gall we easily saw larvae and a few adults.

How will they overwinter?

More bug love then next year’s galls.

(photos by Kate St. John)

28 August 2020

In case you missed it in early August, here’s amazing news from Kobe University about the way a beetle survives being eaten by a frog.

The frog is the dark-spotted frog in Japan (Pelophylax nigromaculatus), above.

The beetle is a water scavenger beetle, Regimbartia attenuata.

When the frog eats the beetle, the beetle is (obviously) inside the frog’s digestive tract which resembles a long cave. Spelunca is Latin for cave.

The beetle actively crawls through the digestive tract to escape out the vent (anus) of the frog. Bugs that don’t keep moving don’t make it out alive.

Kobe University provided this movie to show what happens.

The word “scavenger” in the beetle’s common name may explain why he isn’t repulsed by what he’s crawling through as he goes spelunking inside the frog.

Read more about the study in this 4 Aug 2020 news release from Kobe University: An insect species can actively escape from the vents of predators via the digestive system.

(frog photo from Wikimedia Commons, all other media courtesy Kobe University via this news release)

24 August 2020

This is the time of year to see whirligigs, those shiny water beetles that spin and swim on freshwater surfaces. They gather in large aggregations in late summer and fall and are hard to miss in August.

When you find an aggregation it may contain only one species or more than a dozen. With 700 species in the Gyrinidae family you have to be an expert to figure out who’s who.

Whirligigs swim on the surface, sometimes quite fast, or dive when threatened or to lay eggs.

They have amazing adaptations to fit their lifestyle:

• Their compound eyes are divided into above-water and below-water halves which are able to see best in each environment. They watch for predators (insects, birds and fish) and prey (live or dead insects).
• Their back legs are short paddles for swimming fast. Their front legs are long for grasping prey. The males’ front legs have suckers to hang onto females when they mate.
• Whirligig beetles cannot walk but they can fly. Their wings carry them to other ponds when their own location dries up.
• Adults need to breathe so they carry a bubble of air under their elytra when they dive. The bubble is positioned at the back end of the bug where their breathing parts are located.

See their breathing bubble in this PBS video about nature’s scuba divers:

(photo and image from Wikimedia Commons; click the caption to see the original. videos embedded from YouTube)

p.s. Just for laughs, here’s a whirligig that you can see at any time of year. 😉

22 August 2020

In late August the birds are silent but bugs are busy everywhere. Here are a few examples of recent bugs at work.

Above, pollinators visit green-headed coneflowers (Rudbeckia laciniata) at Moraine State Park.

Below, a midge laid its eggs on a flower head which grew into a huge gall. My guess at the midge’s identity is Asphondylia rudbeckiaeconspicua based on the description and photos posted here by The Michigan Nature Guy.

Fall webworms are building webs and enclosing tree branches as they eat the leaves. The webs protect the caterpillars from predators and can become quite large, as shown below.

The caterpillars won’t permanently damage the trees because the growing season is nearing its end.

See a photo of the adult moth and read more about fall webworms here.

Cicadas are still “singing” in Pittsburgh. Occasionally I find a molted exoskeleton like this one in Frick Park.

And finally, at Duck Hollow I almost walked into a tiny caterpillar dangling from an invisible filament. The caterpillar blows in the wind, his filament touches another tree and he scrambles up. It’s an effective form of transportation. Much faster than walking.

(photos by Kate St. John)