Insects have many techniques for escaping predators. They fly, sting, use camouflage, or contain poisons. The Indian stick insect (Carausius morosus) has none of these skills so it plays dead.
John Skelhorn at Newcastle University wondered if feigning death actually works. Stick insects taste good when they’re alive but taste terrible when dead. Do predators always avoid dead-looking critters? Skelhorn experimented with stick insects and one of their predators to find out.
First, here’s what a living stick insect looks like.
For predators, Skelhorn chose chickens who’d never seen a stick insect — 90 chicken chicks divided into three test groups.
Naive chicks who’d never eaten a dead stick insect were willing to approach those playing dead. However, any chick that had tasted a dead one, moved back and refused to touch the pretender. (Eeeeww! They wiped their beaks.)
Does an insect playing dead live longer? Yes, if the predators have experience.
As human population soars and fish populations plummet illegal fishing has ramped up in the world’s oceans. With 50% of the world’s fish population now gone, countries protect fish within their 200-mile Exclusive Economic Zones (EEZ) but dishonest fishing vessels sneak in to capture endangered species and overfish what’s left.
In 2017 Henri Weimerskirch and colleagues at Centre of Biological Studies Chizé launched an innovative study to uncover the extent of illegal fishing. They equipped wandering albatrosses (Diomedea exulans) with radar detectors that transmit location data to satellites. The research team then matches albatross radar sightings to AIS satellite sightings. If there’s a radar ping but no AIS, the boat is operating illegally.
The research team expanded the study in 2019 by fitting 169 albatrosses from Crozet and two other islands with radar detectors (map below). From December 2018 to June 2019 the albatrosses encountered 353 ships, 37% of which had turned off their AIS.
After a 6-month study with the large seabirds, the researchers estimate that more than one-third of vessels in the southern Indian Ocean are sailing undercover, confirming concerns about illegal or unreported fishing.
Perhaps you’ve noticed that earthworms come out on the sidewalks when it rains. They rise to the surface in damp soil when they hear the pattering of rain above them. Gulls and wood turtles take advantage of this by tapping on damp ground to lure worms to be eaten.
It was only a matter of time before the highly invasive spotted lanternfly (Lycorma delicatula) made its way to western Pennsylvania but it’s disturbing to learn that it’s so close to Pittsburgh.
On 20 January 2020 the Columbus Dispatch reported that spotted lanternfly egg masses were found at the Norfolk Southern railyard in Conway, PA. They probably arrived by train and are now less than 20 miles from Downtown Pittsburgh and even closer to Ohio.
At this time of year the adult bugs are not active so an egg mass, pictured below, is the only thing they found. The authorities scraped away the egg masses and killed the eggs.
This is bad news anyway. USDA says that spotted lanternflies are the worst invasive species we’ve seen in the United States for 150 years.
Learn how to identify them and see why they’re so awful in the video below.
(photos from bugwood.org; click the captions to see the originals)
We’re often so mesmerized by the ant’s struggle that we forget she has an additional challenge. She has to navigate while walking backward. Ethologists at Paul Sabatier University wondered how ants do this so they baked some cookies and ran some tests.
Using a nest of Spanish desert ants (Cataglyphis velox) the scientists laid out large cookie pieces for the ants to find. Without disturbing the ants’ paths scientists noted how often they turned around to check their bearings. They also “airlifted” some ants away from the nest (no path to remember) and messed up the scenery for others so the path would look different.
To give you an idea how hard this is, imagine walking backward without the help of handheld Google/Apple maps. How often would you turn around to check where you were going? And what would you do if an enormous hand rearranged the scenery and nothing looked the same?
Some of the confused ants never made it, but those who knew their path walked 6 meters without peeking. This is equivalent to a human walking backward without peeking for the length of two football fields.
Perhaps it helps that ants can see nearly 360 degrees around their heads. Despite all the challenges they still get home.
Dovekies eat small invertebrates and fish but the majority of their diet is made up of copepods. A single dovekie eats 60,000 of them per day. Quadrillions(*) fall prey to dovekies during the breeding season. So … What the heck is a copepod?
Phytoplankton is really tiny, so small that you need an electron microscope to see it. The Barents Sea bloom above is thought to be Emiliana huxleyi, shown below. The disks are made of calcium carbonate which is also the primary component of seashells. The calcium in phytoplankton makes its way up the food chain.
Thus if phytoplankton is scarce, copepods are scarce and the dovekies starve. That’s how a seabird relies on algae.
(photos from Wikimedia Commons; click on the captions to see the originals)
(*) How many copepods? Here’s a back of the napkin calculation: Suppose there are 50 million dovekies, each one eating 60,000 copepods/day. Dovekies live in their breeding range for four to six months, so there have to be quadrillions of copepods available during that period. Dovekies aren’t the only animal that eats copepods. The numbers are staggering! (My original calculation had a power-of-10 problem. See Tom Brown’s correction.)
Insects that disappeared in the cold came out again during last week’s warm weather. On Wednesday I found a western conifer-seed bug on my front porch.
Formerly restricted to the western U.S., the western conifer-seed bug (Leptoglossus occidentalis, WCSB) has spread across North America, to Europe and South America. At 1/2 to 3/4 inches this “true bug” sucks the sap of developing pine cones and the pulp of pine seeds.
Travel is a tonic for seeing the world in new ways. This month my husband and I spent a week with his sister at Cape Cod where we had new weather, new scenery and new looks at plants I might have seen at home.
Our timing was pretty good. We missed the October 12 nor’easter but were on hand for the October 17 “bomb cyclone.” We didn’t lose power, but it was still very windy on the 18th when I visited Fort Hill, pictured above.
Birds were hard to find that day so I noticed plants such as this European spindle-tree (Euonymous europaeus) with puffy, pink, four-sided fruits.
The puffballs are actually a casing that holds orange fruit within. This ornamental has probably been planted in Pittsburgh, though I’ve never noticed it.
My favorite discovery was a hole in a leaf.
Who ate it? Perhaps this caterpillar did. I found him elsewhere on the plant.
And finally, the sun touched translucent red berries and made them glow at Bell’s Neck.
The small plants have a single leaf midway up the stem (lefthand photo) and were growing among pine needles. Please leave a comment to tell me what they are.
p.s. Thank you to Kerry Givens who identified the red berries as a Canada mayflower and the caterpillar as a Turbulent Phosphila moth.
(photos by Kate St. John except where noted in the captions; click the captions to see the originals)
So many woolly bear caterpillars have crossed my path this fall that, fearing they’d be trampled, I have carefully moved each one across the trail.
“Woolly bears” are the larva form of a common North American moth, the Isabella tiger moth (Pyrrharctia isabella). Since she is not dependent on only one host plant, Isabella is found in many habitats.
She even lives in the Arctic, surviving the winter because she has natural anti-freeze in her cells. Wikipedia describes how she does it:
The banded woolly bear larva emerges from the egg in the fall and overwinters in its caterpillar form when it literally freezes solid. First its heart stops beating, then its gut freezes, then its blood, followed by the rest of the body. It survives being frozen by producing a cryoprotectant in its tissues. In the spring it thaws.
The orange oakleaf butterfly (Kallima inachus), native to tropical Asia, is well named. The underside looks exactly like a leaf when the butterfly closes its wings, and it has wet and dry season forms that mimic the leaves of each season.
The butterfly stands out when its wings are open.
Watch it become a leaf as it flutters in place.
We have leaf-like butterflies in North America, too. Click to see the ventral and dorsal sides of the goatweed leafwing (Anaea andria). It ranges from southeastern Arizona to southern Ohio.