DADDY-LONG-LEGS
IN early September, golf links and other such grasslands swarm with a
large gnat-like fly of reddish-brown body, feeble flight, and long,
straggling legs. These flies are generally called "Daddy-Long-Legs,"
or, by the more learned, "Crane-flies." I find that they are
sometimes confused with another fly of about the same size with
bright reddish-brown body, which is very much less abundant and
occasionally flutters around the lamps and candles in a country house
when the windows are open in the evening. This second kind of fly has
a formidable black-coloured sting, which it shoots out from the end
of its tail when handled; it has also two pairs of wings, and is an
Ichneumon-fly, one of the Hymenoptera, the order of insects to which
bees, wasps, ants, and gall-flies belong. Our daddy-long-legs has no
sting, though the female has a sharply pointed tail. It has only one
pair of wings, and belongs to the order Diptera, or tway-wing flies, in
which our house-fly and bluebottle, horse-flies, tsetse-flies, gnats,
and midges of vast number and variety are classified. They none of them
have tail "stings," though the tail may be elongated and pointed.
[Illustration: FIG. 22.
A, The Crane-fly (Daddy-Long-Legs), Tipula oleracea. _e_, the left eye;
_h_, one of the balancers or "halteres," which are the modified second
pair of wings; _th_, the thorax. Natural size.
B, The "Leather-jacket," the grub of the crane-fly. _a_, head; _b_,
tail. Natural size.
C, The Click-beetle or Skip-jack, Elater obscurus. The line beside it
shows its natural size.
D, The true Wire-worm or grub of the click-beetles. Enlarged to four
times the natural length. _a_, tail; _b_, head.]
Though the two-winged flies or Diptera have only two wings well grown
and of full size, the second or hinder pair of wings which other
insects possess of full size, are present in them in a very much
dwindled condition. Since most of our common flies are very small it is
difficult to see this dwindled pair of wings, which lie close behind
the first or large pair, and are called the "balancers," or "halteres."
The daddy-long-legs (Fig. 22, A) is big as flies go, and with a pocket
lens, or even without one, you can readily see the dwindled second pair
of wings standing out clearly from the body behind the attachment of
the first pair. These "balancers" are of the shape of a tennis racket,
or a ball-headed club. They serve no longer as organs of flight, but
as auditory organs. A minute parasitic insect (Stylops) which lives in
bees has only one pair of wings, but in this case it is the hinder pair
which are developed, the front pair being shrunk to rudimentary lappets.
The daddy-long-legs, or common crane-fly, is a little less than an inch
long and a little more than an inch across the spread wings. Its power
of flight is not well developed, and its six long legs are moved so
slowly and awkwardly that one would say that its powers of walking and
running are also feeble. Their strange movements have led some unknown
poet to imagine the "daddy" saying:
"My six long legs, all here and there,
Oppress my bosom with despair."
In reality these queerly-moving long legs serve the insect effectively
in making its way among the closely-set blades of grass about which
it crawls. The legs easily come off, and the loss of one does not
appear to be a serious matter. Probably the easy detachment of a leg
enables the fly to escape if one of them gets caught and nipped in
overlapping blades of grass--though such a throwing away of a limb
seems a rather reckless proceeding, especially since the insect has
no power of "regeneration" as it is called, that is, of growing a new
leg to replace the lost one. There are several well-known instances
of animals which have the power of breaking off a leg or the tail if
seized by an enemy or otherwise gripped. The smaller lizards and the
legless lizard, called the "slow-worm," have this power in regard to
the tail, but they proceed to grow a new tail after they have escaped.
Some marine worms have a similar faculty, and some star-fishes (hence
called "brittle-stars") have a most annoying habit of throwing off
their "arms" when caught. The central disk of these star-fish, with all
its arms shed, can "regenerate" the lost parts. Crabs, too, of various
kinds have the habit, when caught by the leg, of breaking it off, and
they may often be found with a completely-formed little leg, which
has been "regenerated" or grown afresh, and will in due time attain
full size. The beautiful hairy skin of the tail of the little dormouse
also will come off when the animal is caught by it, leaving the bony
blood-stained skeleton of the tail exposed to dry and wither up. There
is no re-growth in this case. I was horrified when I was a boy to see
six dormice reduced to this condition in the bird and beast shop on the
staircase of the old Pantheon bazaar. They had escaped from their cage
whilst I was looking on, and the shopman endeavoured to catch them,
with this distressing result.
So we find that the loss of its legs by the "daddy" is a means of
safety to it, and is a similar provision to that seen in some other
animals. It seems improbable that the "old father long-legs" who
"would not say his prayers" (according to an ancient nursery rhyme),
is a myth referring to a daddy-long-legs of the insect kind, since the
recommendation to "take him by his left leg and throw him downstairs"
would have been futile; his left leg would have come off as soon
as seized, and have greatly embarrassed the individual intending
to throw him downstairs! Another kind of insect-like animal, which
occurs commonly in cobwebby outhouses, and has a globular body and
eight very long legs--easily broken off--is also commonly called a
"daddy-long-legs." It has no wings, and is allied to the spiders,
though it is not a true spider--having a minute pair of nippers near
its mouth, instead of the pair of stabbing claws which spiders have.
It is frequently called a "harvester," a name loosely applied to other
small creatures. It is known to zoologists as Opilio.
Our crane-flies, or daddy-long-legs, when they swarm about the grass
are intent on two objects. They do not require food; they have had
enough when they were grubs concealed in the soil. They are now busy,
first, in pairing, so that the females' eggs may be fertilized; and,
secondly, the females are about to choose a likely piece of ground in
which to bore with their pointed tails and lay their eggs. They prefer
rather damp spots, shaded from the fierce drying heat of the sun, for
this purpose. When laying her eggs, the female balances herself with
her legs in an upright position, and, pushing the sharp tail into the
earth, moves round by the aid of her legs, to the right and to the
left, so as to bore a quarter of an inch or so into the loose soil.
Then she lays two or three eggs, and, coming down from her upright
pose, moves on through the blades of grass for 3 or 4 inches, and again
takes an upright attitude, and repeats the boring and egglaying. The
eggs are very small, black, shining grains, of which as many as 300 are
found in the body of one ripe female. The male crane-fly has a broad,
somewhat expanded end to its body, by which it is easily distinguished
from the female.
From the eggs minute maggots or grubs hatch and feed upon animal and
vegetable refuse in the soil, but as they increase in size they
burrow an inch or so into the ground among the grass roots. There
are two broods, one in spring and a more abundant one in August and
September. The grubs have no legs. Insect grubs are often legless, as,
for instance, the maggots or "gentles" of bluebottle-flies. Or they
are provided with short legs, as, for instance, are the "caterpillars"
or grubs of moths and butterflies. The grubs of the crane-fly (Fig.
22, B) show eleven rings or segments to the body, and have a tough
grey or brownish skin, which is so firm as to give them the name of
"leather-jackets." They have a head provided with a pair of short,
strong mandibles or jaws, and a very short pair of feelers (antennæ).
These grubs grow to be an inch and a half long, and are two-thirds
the thickness of a common quill pen. They gnaw with their hard jaws
the young shoots and roots of grass, and do an enormous amount of
damage to grassland. They are rarely seen except when a sod is lifted,
but in late spring and summer, when the grub changes to a motionless
pupa or chrysalis, they may be seen protruding for about a third
of their length from the surface amidst the grass tufts. Birds eat
them and rooks dig with their beaks into the sod in order to pull
them out, leaving a number of small pits (on the golf links) where
they have been at work. The proper name of these injurious grubs is
"leather-jackets." They are often confused with another grass-and-wheat
pest, the "wire-worm," and are in consequence sometimes called "false
wire-worms." The "wire-worm" is the grub of a beetle (Fig. 22, C
and D), and is very different in appearance and history from the
"leather-jacket," though both of them do great damage to grass and to
grain crops.
The common crane-fly, or daddy-long-legs, is called Tipula oleracea by
entomologists, and is abundant in Europe as well as in these islands.
There are other "species" of the genus Tipula common in England,
namely, a smaller kind with spotted wings, Tipula maculosa, or the
spotted crane-fly, and a large kind called Tipula paludosa, which
frequents marsh land. There are many species of Tipula in other parts
of the world, and there are closely allied kinds which are ranked in
distinct genera, differing a little in certain features from the genus
Tipula. These all form, taken together, the family Tipulidæ. They,
together with the various kinds of gnats or "mosquitoes," the midges
and fungus-flies, form one of two divisions into which the two-winged
insects or Diptera are divided, namely, those with long, thread-like
feelers or antennæ (Nemocera--thread horned), the other division
being those with quite short antennæ (Brachycera--short horned). The
latter group comprises the flies with thick, heavy bodies, such as the
common house-fly, the bluebottle, the horse-flies, bott-flies, and
tsetse-flies. The long-horned group have usually long, narrow bodies
and long, narrow wings, which do not at once lie flat on the back
when the fly alights (as do those of the short-horned group, as, for
instance, those of the common house-fly). The females of the common
gnat (Culex pipiens) and numerous allied species are bloodsuckers. The
various midges are mostly harmless, whilst others have females which
suck blood. The crane-flies do not bite. The real feeding of all these
gnat-like flies is done when they are in the grub phase of their life,
but the females of some gnats and midges appear to have the need of
extra nourishment when in the fully-formed free-flying state, in order
to ripen their large bulk of eggs. Hence, in some cases, they (but not
the males) suck the juices of plants and the blood of animals.
The larval or grub phase of life is passed by many of these flies in
the earth amidst putrefying vegetable and animal refuse on which they
feed, as in the instance of the daddy-long-legs; but here and there we
find species which penetrate into the soft parts of plants and animals.
A whole group of many species burrow into mushrooms and other fungi
when they are grubs; others, again, live in water when they are grubs
or "larvæ," and have a very active aquatic life, rising to the surface
to breathe air and searching for food in the water with their feelers
and eyes, and seizing it with their powerful jaws. The mother fly in
these cases lays her eggs in a group on the surface of the water or
embedded in a jelly which she secretes and attaches to the leaves of
water plants. Some of the short-horned flies (bott-flies and others)
lay their eggs in the living flesh of warm-blooded animals, including
man, and the maggots hatch there and feed on the juices of the
"flyblown" animal. Cases are not rare of children being thus infested.
The black flies which fly in swarms "high" or "low" in the country
lanes on summer evenings are not true biting gnats, but a large kind
of midges known as Chironomus or Harlequin flies. Their eggs are laid
in the water of ponds, and the larvæ on hatching bury themselves
in the rich black mud and feed there. The larvæ are of a splendid
blood-red colour, and are often called "blood-worms." They owe their
colour to the presence in their blood of the same red oxygen-seizing
crystallizable substance, hæmoglobin, which gives its red colour to
the blood of man and other vertebrates. Its presence is remarkable,
because in all other insects the blood is colourless or of pale blue or
green tint. It seems that this hæmoglobin renders service to the larvæ
of the big midges as it does to some other creatures which live in
impure water, where free oxygen is very small in quantity, namely, it
enables them to absorb and hold by loose chemical combination the small
quantity of oxygen available. The minute midges called "Hessian fly"
and "Cecidomyia"--injurious to cereal crops--should be mentioned here
as among the allies of crane-flies, as also the blood-sucking midges,
Ceratopogon, and the minute blood-sucking sand-flies or Buffalo-flies,
called "Simulium." Species of Ceratopogon, so minute as to be barely
visible, cause terrible annoyance by their bites to the salmon-fisher
in Scotland, where they often swarm in countless numbers. The
Buffalo-flies attack man, but in some districts of North America alight
in thousands on cattle, and cause death in a few hours. A harmless
long-horned fly is "the plumed fly," Corethra, the large aquatic larva
of which is glass-like and quite transparent, and offers splendid
facilities for microscopic research. I used to take it every year in a
pond near Hampstead Heath.
The leather-jackets, or grubs of the common crane-fly (Fig. 22,
B), sometimes destroy hundreds of acres--even whole districts--of
grassland in England and France by gnawing the young subterranean
roots and shoots of the grass. They also destroy young wheat crops.
The leather-jacket is regarded by agriculturists as an intractable
pest, since it gets too deep into the turf to be destroyed by chemical
poisons. Its thick skin also makes it very resistant to such treatment.
When immersed in brine for twenty-four hours the grubs are not killed;
prolonged immersion in water is equally ineffective; they may be frozen
until they are brittle, and will yet recover; and when kept three weeks
without food, still remain alive. Birds are their natural enemies, and
rooks not only dig after the grubs, but swallow the flies at the rate
of four a minute! Ploughing up the land in which the grubs abound is
recommended as a means of destroying them, and also the application
of gas-lime to the ground. Rolling the turf and pressing it down also
kills the grubs, but the best chance of diminishing their ravages is
found in draining wet land and in feeding up the young grass plants
with "fertilizers," so that they may grow rapidly and resist the
injurious effect of the leather-jackets' nibbling.
Before leaving this subject it will be found interesting to contrast
the "leather-jacket" with the true "wire-worms," which are the grubs of
a remarkable kind of beetle (there are half a dozen British species)
called the click-beetle (Fig. 22, C). They belong to a great family
of beetles (Coleoptera), known as the Elaterids or Elaters, of which
7000 species are known, sixty being British. Some of the most brilliant
light-giving or phosphorescent insects (not, however, the common
glow-worms) belong here. The click-beetles are so called because when
one is laid on its back it regains its proper pose, with the legs
beneath it, by a spring or "skip," accompanied by a sharp click. The
grubs of the click-beetles, known as "wire-worms" (the name is also
applied to centipedes), are more threadlike, that is to say narrower,
than the leather-jackets. They are not legless "maggots," but have
three pairs of small legs (Fig. 22, D). They destroy corn and grass,
and do not change into the adult condition in a few months, as do the
leather-jackets, but remain for three, and in some cases five, years
in the ground feeding on the roots of the corn and grass plants, doing
much destruction before they finally change into beetles.