Walk into my Parlour – A Blog about Flies
(This post mainly covers Diptera but also includes Spiders and other small invertebrates that are not insects.)
This is one of three blogs about insects. See also  Lepidoptera (and Odonata) and  Hymenoptera (and Hemiptera and Coleoptera). Blog  also has a general introduction to the world of insects.
I have taken pictures of insects over the spring and summer in many locations. I won’t say much about where each picture is taken and I will more or less stick to a sort of taxonomic order.
The insect order Diptera are flies but sometimes we have to call them ‘true flies’ to exclude many other insects that use the word ‘fly’ (such as damselflies, mayflies, scorpion flies …) The word ‘diptera’ comes from the Greek for ‘two wings’ because these insects use just one pair of wings to fly. The hindwings have become ‘halteres,’ tiny stubs that can help the insect to perform some advanced aerobatic manoeuvres.
It’s a large order with about a million species (only about 125 000 formally described) in dozens of families. To a non-expert most of the ones that are large enough to be seen more or less look like flies – although crane-flies with their elongated bodies are not so typical and some hover flies try to look like bees or wasps (or other insects.)
Flies have a mobile head, with a pair of large compound eyes, and mouthparts designed for piercing and sucking or for lapping and sucking. They have great manoeuvrability in flight, and claws and pads on their feet enable them to cling to smooth surfaces (including ceilings.) They undergo complete metamorphosis. The eggs are laid on the larval food-source and the larvae, which lack true limbs, develop in a protected environment, often inside their source of food. The pupa is a tough capsule from which the adult emerges when ready. Flies mostly have short lives as adults.
Syrphidae, normally called Hoverflies, are the most obvious flies throughout summer with about six thousand species. They vary in size and are generally seen either feeding on nectar from flowers or hovering nearby. (The larvae may feed on decaying plants and animals or other small insects.) Many of them are brightly coloured and mimic more dangerous bees and wasps.
[I won’t attempt to explain the difference in usage between ‘Hoverflies’, ‘Hover-flies’ and ‘Hover Flies’ etc. and I may not even be consistent in my own usage!]
There are several anatomical differences that distinguish hoverflies from other flies. Apart from the colourful bodies there are usually two identifying features in the wing veins. Hoverflies have a false rear edge to the wings and a spurious longitudinal vein. I find that the best ways to tell hoverflies from other flies and identify them is to post pictures on Facebook where UK Hoverflies and UK Diptera both have excellent groups. I normally get species identification within hours although some male insects can only be identified to genus without a detailed microscopic examination.
Here is a typical hoverfly, Syrphus Sp (male.) Males are generally recognized by larger eyes that almost touch at the centre.
I have cropped and enlarged the picture above to show one wing and I have marked the key features – the spurious vein (RED) and false rear edge (BLUE.)
Most hoverflies just have a scientific name. Common names when they exist are not standardized. In no particular order here are another Syrphus (S Torvus,) a Parasyrphus (P punctulatus) and an Episyrphus (E balteatus, sometimes called a Marmalade Fly,) then Eristalis Pertinax and E Tenax, Epistrophe eligans, Melanostoma scalare (two pictures) and Syritta pipiens.
I won’t attempt to identify the differences in these flies, which are basically yellow and black in appearance. Next we have Chrysogaster solstitalis, Meliscaeva auricollis, Helophilus pendulus (sometimes called a Sun Fly), Parhelophilus Sp., Cheilosia illustrata and Myathropa florea.
Sphaerophoria scripta, Xanthogramma pedissequum, and Merodon Equestris (Narcissus Fly) will be immediately recognizable for you.
I have left some of the large prettier ones until last. Here are Leucozona glaucia, L laternaria, L lucorum (two pictures), Volucella pellucens and V zonaria (two pictures.)
This last fly, known as the Hornet Mimic Hoverfly is the largest of those found in England.
Tipulidae – called ‘Daddy Longlegs’ in Britain, but not elsewhere – have elongated bodies. Most of them do not feed once adult. We have about 300 species, generally very small. The larger ones are species of Tipula or Nephrotoma.
A closely related family is the Ptychopteridae, Phantom Crane-flies. Here is Ptychoptera contaminata.
We have about 5000 species of flies in Britain from many different families. Without a microscopic examination of a pinned dead specimen you can generally get to the family and sometimes the genus. I have about twenty more families to show you. I will do them by family (briefly!) in alphabetical order.
Here are representatives of the families Bombyliidae (Bombilius Major, the Bee Fly); Bibionidae (Bibio sp, a St Mark’s Fly); Calliphoridae (Calliphora vicina a blue bottle); Chironomidae; Chloropidae (Thaumatomyia notata a tiny grass fly); Dolichopodidae (Poecilobothrus nobilitatus the Semaphore Fly) and Empididae (Empis livida a Dance Fly or Dagger Fly with its long mouth.)
Next we have Micropezidae; Muscidae (Mesembrina meridiana, the colourful Noon Fly); Psychodidae (Pericoma sp, the Moth Fly or Drain Fly); Rhagonidae (Chrysopilus asiliformis, the common Snipe Fly); Rhinophoridae, woodlouse parasites (Rhinophora lepida); and two from Sarcophagidae (a female and male Sarcophaga sp.)
Now we have Sepsidae (Sepsis Fulgens, an ant mimic fly); Stratiomyidae, Soldier Flies (Chloromyia Formosa, the Broad Centurion, two pictures); Tabanidae, Horse Flies (Tabanus sp); Tachinidae (Estheria cristata and Tachina fera) and Tephritidae (Terellia tussilaginis.)
I didn’t want to leave out the next four but I haven’t been able to identify them even to family level.
We have seen that Insects are included in Arthropods, the phylum that also includes lobsters and shrimps. If we go down another branch via Chelicerates and Arachnids we get to the order Araneae or Spiders, terrestrial animals with an exoskeleton but having eight legs unlike the six of an insect.
There are other differences. In spiders the head and thorax are fused into a cephalothorax. They do not have antennae but have a pair of pedipalps (much larger in males) a pair of chelicerae and spinnerets producing silk. They have eight eyes and the patterns of the eyes often identify the family. Almost all spiders are predators eating insects and other spiders. [Sometimes the males are much smaller than the females and they have to be careful to avoid being eaten.]
I don’t like large spiders indoors. I normally trap them and release them outside. Just for you I photographed this Giant House Spider, Eratigena atrica before taking it to the garden.
Cellar Spiders, Pholchus phalangioides, are not so bad. They are bigger if you count the very thin elongated legs but the body is much smaller. Here is a close-up.
All of my other spiders were seen outside. Here are Agelena labyrinthica; Amaurobius ferox Black Lace Weaver; Araniella cucurbitina Cucumber Spider; Diaea dorsata a Crab Spider; the Garden Spider Araneus diadematus; Philodromus dispar a Running Crab Spider; Pirata Sp a Wolf Spider and Salticus scenicus a Zebra Spider, one of the jumping spiders.
[As for all animals the scientific name is more standardized than common names.]
Other Arachnids, Arthropods and Others
All Arachnids have eight legs (with pedipalps and chelicerae sometimes almost acting as legs.) Harvestmen (Opiliones) differ from spiders in having a single body that combines the cephalothorax and abdomen. They have just two eyes and quite poor eyesight. I see them sometimes just waiting on a leaf. (They do not make silk.)
Here are Platybunus triangularis and Leiobunum rotundum.
Because of their very long thin legs Harvestmen are sometimes called ‘Daddy Longlegs,’ a name also given to crane-flies and cellar spiders.
Like harvestmen, this tiny Velvet Mite, Trombidium sp, is quite loosely related to spiders and has eight legs. Gardeners call these tiny pests ‘red spiders.’
I just have a few more small animals to include. Here are two woodlice, Armadillium vulgare and A depressum.
Finally a pair of Grove Snails, Cepaea nemoralis.
[Of course snails are hermaphrodites so the word ‘pair’ just means that there were two of them.]
The woodlice just about come in as arthropods but entomology sometimes loosely includes all small invertebrates like these snails.
I have to admit that I put spiders and flies together to fit my title ….
Mary Howitt published a poem called The Spider and the Fly in 1829. It tells the story of a cunning spider who ensnares a naïve fly through the use of seduction and flattery. It’s a cautionary tale against those who use flattery and disguise their true evil intentions.
The opening line, ‘Will you walk into my parlour?’ is one of the most recognized and quoted first lines in all of English verse. Often misquoted as “Step into my parlour” or “Come into my parlour”, it has become an aphorism used to indicate a false offer of help or friendship that is a trap. The line has been used and parodied numerous times in various works of fiction.
“Will you walk into my parlour?” said the Spider to the Fly,
‘Tis the prettiest little parlour that ever you did spy;
The way into my parlour is up a winding stair,
And I’ve a many curious things to show when you are there.”
“Oh no, no,” said the little Fly, “to ask me is in vain,
For who goes up your winding stair can ne’er come down again.”
“I’m sure you must be weary, dear, with soaring up so high;
Will you rest upon my little bed?” said the Spider to the Fly.
“There are pretty curtains drawn around; the sheets are fine and thin,
And if you like to rest awhile, I’ll snugly tuck you in!”
“Oh no, no,” said the little Fly, “for I’ve often heard it said,
They never, never wake again, who sleep upon your bed!”
Said the cunning Spider to the Fly, “Dear friend what can I do,
To prove the warm affection I’ve always felt for you?
I have within my pantry, good store of all that’s nice;
I’m sure you’re very welcome — will you please to take a slice?”
“Oh no, no,” said the little Fly, “kind Sir, that cannot be,
I’ve heard what’s in your pantry, and I do not wish to see!”
“Sweet creature!” said the Spider, “you’re witty and you’re wise,
How handsome are your gauzy wings, how brilliant are your eyes!
I’ve a little looking-glass upon my parlour shelf,
If you’ll step in one moment, dear, you shall behold yourself.”
“I thank you, gentle sir,” she said, “for what you’re pleased to say,
And bidding you good morning now, I’ll call another day.”
The Spider turned him round about, and went into his den,
For well he knew the silly Fly would soon come back again:
So he wove a subtle web, in a little corner sly,
And set his table ready, to dine upon the Fly.
Then he came out to his door again, and merrily did sing,
“Come hither, hither, pretty Fly, with the pearl and silver wing;
Your robes are green and purple — there’s a crest upon your head;
Your eyes are like the diamond bright, but mine are dull as lead!”
Alas, alas! how very soon this silly little Fly,
Hearing his wily, flattering words, came slowly flitting by;
With buzzing wings she hung aloft, then near and nearer drew,
Thinking only of her brilliant eyes, and green and purple hue —
Thinking only of her crested head — poor foolish thing!
Up jumped the cunning Spider, and fiercely held her fast.
He dragged her up his winding stair, into his dismal den,
Within his little parlour — but she ne’er came out again!
And now dear little children, who may this story read,
To idle, silly flattering words, I pray you ne’er give heed:
Unto an evil counsellor, close heart and ear and eye,
And take a lesson from this tale, of the Spider and the Fly.
[When Lewis Carroll was finishing Alice’s Adventures Under Ground for publication he replaced a parody he had made of a negro minstrel song with a parody of Howitt’s poem. “The Mock Turtle’s Song”, in Alice’s Adventures in Wonderland, is a parody of The Spider and the Fly. It mimics the metre and rhyme scheme, and parodies the first line, but not the subject matter.
“Will you walk a little faster?” said a whiting to a snail,
“There’s a porpoise close behind us, and he’s treading on my tail …]