Rare caterpillars on video

This 18 July 2019 video is by Luuk Punt. On the Maasvlakte in the Netherlands, he made this footage about a spurge hawk-moth caterpillar.

This is a rare species in the Netherlands. But now there seems to be an invasion. Luuk Punt saw at least forty caterpillars. They may be 8 centimetres long.


Great tits and oak processionary caterpillars, cartoon

Great tits cartoon

This cartoon, from today’s Dutch Metro daily, is by René Lensink.

The caption says, translated: number of oak processionary caterpillars tripled.

In the cartoon, a young great tit says to its mother: Mum, I don’t want these foul caterpillars! I prefer a fat fast food snack!

Great tits are one of few bird species eating caterpillars of oak processionary moths; which can be a nuisance in the Netherlands and elsewhere.

Today in the Netherlands, primary schools have been closed and hockey matches postponed because of oak processionary caterpillar trouble.

To be 100% biologically corect, the young great tit‘s belly in the cartoon should have been a paler yellow than the adult’s.

Hummingbird hawk-moth, early this spring

This 18 March 2019 video is about a hummingbird hawk-moth in a garden in Gouda town, the Netherlands. It is early for that species this spring.

Even in February, a few hummingbird hawk-moths were already present in the Netherlands. Usually, they winter in southern Europe and come to the Netherlands later. But lately, some of them winter in the Netherlands.

S. Reilingh made this slow motion video.

Deaf moths’ sounds to escape from bats

This 2010 video says about itself:

Development of the Orchard Ermine (Yponomeuta padella) from caterpillar to moth. Filmed at the Wollenberg, Hesse, Germany.

From the University of Bristol in England:

Deaf moth evolves sound-production as a warning to outwit its predator

February 5, 2019

A genus of deaf moth has evolved to develop an extraordinary sound-producing structure in its wings to evade its primary predator the bat. The finding, made by researchers from the University of Bristol and Natural History Museum, is described in Scientific Reports today [Tuesday 5 February].

It’s already known that some species of moth have evolved a range of defensive mechanisms to evade insectivorous bats’ highly-tuned echolocation (biosonar) detection skills. The discovery of a wingbeat-powered sound producing structure in the wings of a deaf moth is completely new.

Many larger species of moth use ears tuned to detect the echolocation calls of bats to provide an early warning of approaching bats allowing them to perform evasive manoeuvres. While others, such as some silk moths, have hindwing tails that produce salient echoes which act as false targets to bats — like the towed decoys fighter planes use against radar guided missiles.

The team of researchers from Bristol’s School of Biological Sciences and the Natural History Museum, London, were studying a group of smaller British moths known as the small ermine moths (Yponomeuta species), and discovered that despite their lack of hearing they were making continual clicking sounds whenever they fly. Unlike other species of moths, that produce sound in response to detecting an approaching bat, small ermine moths have evolved to produce continual warning sounds.

The sounds these moths produce are very similar to sounds produced by larger moths, such as the tiger moths, which warn bats of the moth’s distastefulness or toxicity (known as acoustic aposematism). At night an unpalatable moth cannot provide a bat with a conspicuous warning colour, so instead it warns its predator acoustically. The team suggest that small ermine moths are acoustically mimicking unpalatable, sound producing moths, to warn bats of their own distastefulness.

Typically, anti-bat sounds are produced by structures called tymbals, small areas of thin cuticle on a moth’s body, which are connected to a muscle. As the muscle contracts, the tymbal buckles and produces a click, then as the muscle relaxes, the tymbal snaps back to its resting state and produces another click. However, the wing-based tymbals of small ermine moths are not connected to a muscle, instead sound production is initiated by the moth’s wingbeat during flight.

Liam O’Reilly, the study’s lead author and a PhD student at Bristol’s School of Biological Sciences, said: “Bat defences in larger moths are well studied, however, the defences in smaller moths are not.

“Many animals use a conspicuous visual signal such as bright colouration to warn their predators of a defence, but at night an unpalatable moth cannot provide a bat with a visual warning signal, so instead it warns its predator acoustically through a clear sound — loud high frequency (ultrasonic) clicks.

“The fact that sound production in these moths has remained undiscovered for so long reminds us of how little we know of the complex acoustic world of bats and moths.”

Following this discovery, the team are working with material scientists to find out the exact mechanism by which the small ermine moth tymbal produces sound. Specialists in buckling mechanics are working on modelling the system to artificially recreate the sounds of these moths.

How hummingbird hawkmoths fly, new research

This July 2016 video says about itself:

Hummingbird hawk-moth – Macroglossum stellatarum in slow motion

A Hummingbird hawk-moth feeding on my window-sill at 120 frames per minute.

From Lund University in Sweden:

Antennal sensors allow hawkmoths to make quick moves

December 20, 2018

All insects use vision to control their position in the air when they fly, but they also integrate information from other senses. Biologists at Lund University have now shown how hawkmoths use mechanosensors in their antennae to control fast flight manoeuvres.

When the moths need to rapidly change direction and manoeuvre, for example to escape predators, their eyes are insufficient. Instead, the receptors at the base of the moths’ antennae provide the necessary feedback. Researchers from Lund University, in collaboration with Sanjay Sane from the Tata Institute of Fundamental Research, Bangalore, have now explored the role of these antennal sensors for flight control, using the hummingbird hawkmoth (Macroglossum stellatarum) as their study model.

In their experiments, the researchers used the moths’ natural habit of hovering in front of a flower when they feed on nectar. They trained moths to visit an artificial flower to drink sucrose solution. Then they moved the flower sideways, at different speeds, while filming their responses with a high-speed camera to see how well they were able to follow the flower movements. To understand what role of the antennal sensors, they clipped the antennae, thus blocking the sensory input, and repeated the same experiment.

“Without antennae the moths were still able to fly, but they were only able to track the slow flower movements, not the fast ones. When we re-attached the antennae they worked nearly as well as before and the moths were able to track the faster lateral movements again,” explains Almut Kelber, professor at the Department of Biology at Lund University. “This is because their antennae function exactly like a gyroscope in aeroplanes. The gyroscope measures the orientation of the plane, or in this case, the moth.”

When it comes to speed, the compound eyes have no chance of matching the feedback from the moth’s “gyroscope.” The transduction of sensory information into a nerve impulse takes 1000 times longer for photoreceptors in the eye than for a mechanoreceptor. In addition, the information from the photoreceptors in the eye has to pass a larger number of neuronal connections in the moth’s brain before it reaches the muscles that control the wings. This longer chain of command adds to the delay of the visual sense compared to mechanoreception.

“Until now, researchers have believed that hummingbird hawkmoths only use visual information to navigate. This was only known from nocturnal moths before. We demonstrate that they also use antennal receptors, and showed how they work together with the visual sense,” says Almut Kelber.

Hawkmoths are not the only insects to use such a “division of labour” between vision and mechanosensation. Flies have long been known to use mechanosensory information from their vestigial hind-wings, small club-shaped structures called halters, in addition to visual information from their eyes.

“We showed that flies and hawkmoths use the same strategy to control their flight, despite very different anatomical prerequisites. They use vision for slow movements and the gyroscope for faster movements. Moths do not possess halteres, but their gyroscopes are in their antennae,” concludes Anna Stöckl, now at the University of Würzburg and one of the researchers behind the study.