The Metamorphosis of the Extraordinarily Snake-Like Elephant Hawk-Moth Caterpillar
Each caterpillar that you are fortunate enough to see eventually goes through an almost-magical transformation into either a butterfly or a moth. In the larval period of their life, they are multi-legged crawling creatures much like children who must learn to crawl before they walk - except caterpillars crawl, then fly as winged insects.
One of the 20,000 or so distinct species of caterpillars that is fascinating to observe is the elephant hawk-moth caterpillar (Deilephila elpenor), which eventually transforms into a brightly-colored moth, although the holometabolous (complete metamorphosis) process itself is somewhat disgusting. The yucky part is what actually occurs on the inside of a moth's cocoon, and I have shared the gruesome details with you further in this article.
Elephant hawk-moths are very strong fliers. They have the ability to beat their wings very quickly and hover into position during feeding. That ability explains the "hawk" part of their name.
The Habitat of the Moth and the Caterpillar
The moths are distributed throughout much of England, Wales, Northern Ireland, and portions of Scotland. The moths usually prefer rosebay willowherbs but can be found in various habitats where this type of vegetation grows. They like waste ground and clearings, rough grassland, woodland areas, or sand dunes, to name only a few. If you live in one of the areas listed above, you might even see them in your own garden, especially if you have brightly-colored flowers growing.
The elephant hawk-moth caterpillar is usually seen around gardens searching for a place to pupate. It is one of the most common caterpillars in the British Isles and grows to about 3.5 inches long. When preparing for pupating the fully grown caterpillars can usually be found high up in the food plants during the daytime. When feeding is ceased, you might find one basking in the sun on your patio or lawn. They have occasionally been found inside homes but it is believed that they were most likely picked up by a pet cat and carried inside.
The Scary Caterpillar Turns Into a Lovely Moth
What Happens Inside a Cocoon
Holometabolous insects undergo radical changes (body form, lifestyle, diet) as they transform through complete metamorphosis. A caterpillar actually digests itself inside the silky cocoon that it created for itself. As a matter of fact, that digestion is the first thing to occur once the cocoon is completed. When this happens, enzymes are released that dissolve all of the tissues. You might think about the inside of the cocoon at this time as a kind of caterpillar soup.
Groups of cells referred to as imaginal discs for each of the body parts a moth will need (wings, legs, eyes, etc) are able to survive the digestive process. Those organized cells were grown when the caterpillar was still developing inside its egg. You may not be aware that certain caterpillars crawl along with tiny rudimentary (flightless) wings neatly tucked inside their bodies.
When the caterpillar's tissues have all been disintegrated, the imaginal discs use the protein-packed soup surrounding them to feed the cell division necessary to form genitals, wings, legs, eyes and all of the other features of an adult moth. Moths are believed by some scientists to remember the things they learned in the late stage of life as a caterpillar.
From an Egg to a Caterpillar
Female moths lay their eggs on the leaves of the plants on which they have been feeding. Depending upon the temperature, the eggs usually hatch within about a week to 10 days. When the caterpillars are about a day old they are less than a quarter of an inch long and a pale green color, although with a noticeable black tail spike. They can be difficult to see hidden among the green leaves.
After about 9-10 days, they are a little over an inch long and begin to display the first signs of the eye-like markings visible on the dorsal area close to the head.
After about two weeks, they are even larger and being moulting from green to a darker form. Some look almost black with the distinctive markings that resemble eyes. They are fully grown after about 30 days.
The most common coloring is a mix of various shades of brown and grey although green ones are common as well, and occasionally some caterpillars are found that are almost solid black.
Dangerous-Looking, Non-Poisonous Facade
Despite a bright and colorful appearance, elephant hawk-moths (as either caterpillars or moths) are not poisonous. They are harmless to both people and pets.
Their fierce look as a caterpillar is merely a facade. If threatened by a bird or other possible prey, they retract their heads and puff out their protuberant necks. Their "costume" of sorts comes complete with fake eyes giving the prey reason to believe that they are snake-like and dangerous.
- Kingdom: Animalia
- Phylum: Euarthropoda
- Class: Insecta
- Order: Lepidoptera
- Family: Sphingidae
- Genus: Deilephila
- Species: D. elpenor
- Scientific Name: Deilephila elpenor
- http://www.animalspot.net/elephant-hawk-moth.html#Habitat:_Where_do_Elephant_Hawk-Moths_Live (Retrieved from website 8/01/2018)
- https://butterfly-conservation.org/moths/elephant-hawk-moth (Retrieved from website 8/01/2018)
- https://www.woodlandtrust.org.uk/blog/2018/07/elephant-hawk-moths/ (Retrieved from website 8/03/2018)
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© 2018 Mike and Dorothy McKenney