Flying insects, new study


This video from Lund University in Sweden says about itself:

27 September 2017

A tobacco hawkmoth flies at different speeds in a wind tunnel.

(Video: Kajsa Warfvinge)

From Lund University in Sweden:

New study changes our view on flying insects

September 29, 2017

For the first time, researchers are able to prove that there is an optimal speed for certain insects when they fly. At this speed, they are the most efficient and consume the least amount of energy. Corresponding phenomena have previously been demonstrated in birds, but never among insects.

Previous studies of bumblebees have shown that they consume as much energy in forward flight as when they hover, i.e. remain still in the air. New findings from Lund University in Sweden show that this does not apply to all insects.

Biologist Kajsa Warfvinge, together with her colleagues at Lund University, has studied the large moths known as tobacco hawkmoths or Manduca sexta. The results show that these moths, like birds, consume different amounts of energy depending on their flight speed. Flying really slowly or really fast requires the most effort.

The discovery may help other researchers who study how insects migrate from one environment to another.

“I imagine that our results could be used indirectly to predict how well different species respond to changing temperatures in view of global warming. By knowing how much energy is needed to fly at different speeds, we can calculate how far and fast the animals can travel given a certain amount of energy,” says Kajsa Warfvinge.

The experiments were performed in a wind tunnel. Using a specially developed technique known as tomographic PIV, the researchers can record the way the air moves in three dimensions when the tobacco hawkmoth flaps its wings. The vortices left in the air can be seen as the insect’s aerodynamic footprint. The vortex strength reflects the amount of kinetic energy added by the insect, which in itself is a measurement of how exerting it is to fly at different speeds.

The results show that classic aviation theory can be applied also to tobacco hawkmoths; that is, it takes a lot of energy to fly slowly (one metre per second), since it is difficult to create lift at these speeds. The same applies when insects fly fast (four metres per second), but here it is the air resistance that makes the flight less efficient from an energy perspective.

“We demonstrate that moths have the same U-shaped relationship between speed and power as birds and aircrafts do. Flying slowly or fast is exhausting and requires more energy. You could say that flying at a moderate speed is optimal. The most energy-efficient speed for these moths is 2-3 metres per second,” says Kajsa Warfvinge.

However, the aim and purpose of the flight determines which speed is most beneficial. If the moths want to stay in the air for as long as possible, they should preserve their energy and maintain a speed of about 2.5 metres per second. If the goal is to fly far, they should increase their speed to about 4 metres per second. Despite the air resistance and the fact that they are unable to fly for the same amount of time, this is the optimal speed for long distances.

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American tussock moth caterpillars videos


This video from the USA says about itself:

13 September 2017

Banded Tussock Moth caterpillar (Halysidota tessellaris) comes in a variety of colors – this is the white variety. Called “Tussock moth” for the tufts of hair on the caterpillar. (tussock = a tuft or clump of green grass or similar verdure, forming a small hillock–Wiktionary).

The long black and white “lashes” front and rear shout out – danger! “Don’t touch me”. Indeed they are akin to extremely small sharp needles. A skin irritation and sometimes a severe allergic reaction can occur when contacting the sharp spines which are said to have a feel like rubbing raw fiberglass threads into your skin. This one is in a rush to pig out and then cocoon-up for the winter! The wildest looking variety of Tussock Moth caterpillar, the white-marked can be seen below here.

It’s wild caterpillar time again on the deck, last year I didn’t see this caterpillar until October – what does that mean for winter?

This video from the USA says about itself:

2 November 2013

The Sound of Caterpillar Footsteps – I captured the sound of the footsteps of this caterpillar’s six big feet doing the double-time down a deck railing (from 00:10 to 00:30) – despite a loud leaf blower in the distance.

A fascinating creature, and one of the more bizarre caterpillars in nature – the larva of the White-Marked Tussock Moth is a combination of stunning beauty and obvious danger and knows how to struts its stuff. With a “toothbrush” on its back, cactus-like needles all over and red warning lights this caterpillar is shouting out – danger! “Don’t touch me”. … Nevertheless, these are interesting creatures to hang with for a short time as they always seem to be in a hurry to get somewhere.

Rare spurge hawk-moth caterpillars in Dutch nature reserve


This 24 August 2017 video is about rare spurge hawk-moth caterpillars, found in the Millingerwaard area of Gelderse Poort nature reserve in Gelderland province in the Netherlands.

This year, there are also more swallowtail butterfly caterpillars in the Gelderse Poort than usually.

Cabbage moth caterpillars hatch, video


This 28 June 2017 video is about cabbage moth caterpillars hatching from their eggs on a Indian cress leaf.

In spite of its name, the plant is originally from South America, not India.

Nel Appelmelk made this video in her garden in the Netherlands.