Metamorphosis of the Rat-tailed fly (Eristalis tenax)
Following
on from my historical art article named ‘Volucellae and Bees’ I have found another piece of art illustrating
hoverflies, which I wanted to share.
This is
from a French book by Emile Blanchard titled ‘Metamorphoses, mœurs et instincts
des insects (Insectes, myriapodes, ararchines, crustaces)’ Published: Paris, G.
Baillière: in 1868, although I have only seen the 2nd edition published in
1877.
Metamorphosis in insects is the book’s subject matter written 24 years before Beddard’s book on mimicry called Animal coloration. As I do not read French the starting point
for my interest was the English version of the book, but I did use translation
software to read Blanchard’s original text about Syrphidae which was
fascinating.
E.
Blanchard’s book was adapted for English readers by P. M. Duncan F.R.S titled ‘The
transformations (or metamorphoses) of insects: (Insecta, Myriapoda, Arachnida,
and Crustacea.)’ and is a compilation of works from other scientists of the era
George Newport, Charles Darwin but mainly the work of E.Blanchard. Publication/Creation: London, Cassell Petter &
Galpin, 1882.
I have extracted from the book one plate called the
‘Metamorphoses of a rat-tailed fly’ which I would like to discuss in more
detail.
The
etching above is of a Common Dronefly (Eristalis tenax). The illustrator of
this art is Louis Rouyer (interestingly his name was removed from the English
adapted version of the book.) and the title changed from Metamorphoses De
L’Eristale Gluant which translates as ‘the Slimy Eristalis’ to ‘The
Metamorphoses of the Rat-tailed Fly’, thankfully neither name used today.
The illustration shows three adults and three
larvae. The adults of the Common Dronefly have a loop on one of the veins in the wing, as in the picture below. The adult I
have most difficulty in determining if there is a loop in the wing is the one
by the pool, although its size, colouration and form would suggest it is a
replication of the same specimen that is airborne and the one drying itself on
the wooden post sticking out of the pool. The reason for looking for this vein
is to determine how accurate the etching might be, this loop in the wing is clearer on the P.M.Duncan version below rather than the imprint above.
Diagram 1: Typical wing of a Tapered Dronefly (Eristalis pertinax) but the loop is the same on a Common Dronefly.
The one sitting on the wooden post looks to
be male as there is no gapping between the eyes. The adult flying, and the one
on the ground, are potentially female as there is a gap between the eyes. Each adult
is depicted as a black fly with no obvious markings on the abdomen, except from
the one in flight which has a lighter colouration on tergite 2, the section of
abdomen closest to the thorax. These markings on tergite 2 are typical of a
Common Dronefly.
In the pool are three larvae with long tails,
often referred to in books as rat-tailed maggots and thus the emerging adults referred
to here as rat-tailed flies. This name for the adult is thankfully no longer used,
although the generic name is still used for all larva with such long tails. The
pool is shallow and full of decomposing leaf litter that may have fallen off
the Willow tree central and to the left of picture. The wooden post is at an
angle rather than upright, depicting to me that this pool is unmanaged and the
post therefore left to rot. It gives the image of a place forgotten, secluded
and a place where such hoverflies might choose to breed and develop.
Common Droneflies are known to have larva
with long tails, but I am unsure about the depiction of eyes on the larva as they
are not morphologically present in real specimens. If I compare the
larva with photographs in the Colour Guide to Hoverfly larvae by G.E. Rotheray each are clearly showing little prolegs which are anatomically correct.
The larvae use their tails as a breathing apparatus, a snorkel to get oxygen
from the surface, and the illustration shows two of the larvae clearly have their
tails protruding out of the water. I am unsure what the grass is at the side of
the pool, but the grass and the wooden stump would be an ideal place for the larva
to crawl out to pupate, before metamorphosing into an adult. What I am not
seeing are any pupa from which the adult will eventually appear. I might assume
that the adult on the post is drying or warming itself after pupation as there
is a bright light shining upon it, as seen by the casting shadow from the
lamella of the plant onto the post. Hoverflies often sit in the sun basking, to
warm-up, so it would be wrong to assume that this one is freshly hatched, but
it could be.
I think it’s a wonderful illustration of the Common
Drone fly implying the larvae and adult lifecycle, it tells me story about the
biological aspect of this species, the habitat where the larva develops.
Illustrators like L.Rouyer contributed to the aesthetic dimension of natural
history at a time when photography was not yet practical for scientific documentation.
They would have helped entomologists distinguish between closely related
species and would have appeared in much of the literature of the time. The book
contains many other fascinating etchings that are worth reviewing, all from
other illustrators. The next picture in the book being the metamorphosis of flesh
flies (Sarcophaga carnaria), showing the maggots crawling in the breast of a
dead bird and a pile of pupa to the side, with a couple of adult flies coming
in to lay more eggs. There is also a wonderful etching of Clubbed general soldier fly (Stratiomys
chamaeleo) all worthy of a look see links below.
Further information about the Authors:
Emile Blanchard was a French zoologist and entomologist (1819-1900)
Credit: A. Féret / P. Petit - Wellcome Collection gallery (2018-03-29): https://wellcomecollection.org/works/ag9v5j7m
Peter Martin Duncan F.R.S (1821 – 1891)
Born in
Twickenham in 1821, he was educated in England and Switzerland before becoming
an apprentice of medicine in London. He qualified as a medical practitioner and
took over a practice in Colchester where he was mayor twice, 1857 for two terms.
His scientific work includes papers on corals and sea urchins, and he was a prominent
archaeologist as well as researcher in paleontology and geology. But in
relation to this blog, he was instrumental in the adaptation for English
readers of Emile Blanchard’s book published (1882) when he was professor of
Geology at Kings College London. He translated E. Blanchard’s book and included
other works from Charles Darwin and George Newport amongst other eminent naturalists/scientists
of the time. He died in 1891 after a period of ill health.
This below is the
replicated picture for the book by Peter Martin Duncan.
If anyone knows
why the illustrator name was removed for the English version, please comment
below.
References
https://en.wikipedia.org/wiki/%C3%89mile_Blanchard
https://www.biodiversitylibrary.org/item/132913#page/5/mode/1up
No comments:
Post a Comment