14 GNATS OK MOSQUITOES — CHAPTER I has written on the Culicidce, and, for our purposes it will be best to confine ourselves to the wing of the mosquito and the names that have been most commonly used by those who have written on the family. Commencing with the anterior border of the wing, we find that it is formed of a strong chitinous rib, which is called the costa. It tapers off externally, but in the Gulicid(B is continued round the entire border of the wing, though this is not the case in all Diptera. 2. AB a A 5 h A f i. — Wing of C. concolor, B,. Desv., ^ to illustratk the Terminology of the Wing in the Culicid^. C,costa.
a, auxiliary vein.
1 to 6, first to sixth longitudiual veins and their branches. 7, seventh, or false longitudinal vein (unsealed).
VI, unsealed vein, between fifth and sixth longitudinals.
h, humeral transverse vein, s, supernumerary transverse vein. m, middle transverse vein. p, posterior transverse vein. A, costal cells.
B, sub-costal cell.
c, marginal cell.
D, anterior fork cell or first submarginal.
E, second subuiarginal cell. F, fii-st posterior cell. G, hinder fork cell, or second posterior.
H, third posterior cell.
I, first basal cell.
J, second basal cell.
K, anal cell.
L, axillary cell.
31, spurious cell.
Looking now at the root of the wing, we find that the remaining longitudinal ribs, or veins, spring from three main trunks, which are connected together near their base by a somewhat elaborate arrangement of cross bars. From the anterior of these spring two veins, the front one of which is usually called the auxiliary vein ; on account of its being absent in many Diptera, though Theobald calls it the sub-costal and by others it is termed the mediastinal.
POSITION AND TERMINOLOGY OF THE CULICID^ 15 It runs into the costa considerably before the tip of the wing, and the relative position of this point is useful in distinguishing species. The other of the anterior group o£ veins is the first longitudinal, which runs, without branching, to join the costa, close to the tip of the wing. From it, well out towards the middle of the wing, springs the second longitudinal, which divides near the tip of the wing into two branches, though in most Diptera this vein remains single. Two veins spring also from the second of the vein-trunk. These are the fourth and fifth longitudinal veins and both of them become forked, the fourth near the tip of the wing, and the fifth further in. In the outer part of the wing, between the forked second and fourth, may be seen the third longitudinal vein, which is distinct, and fringed with scales only in this outer part of the wing, and often appears to take its origin from a cross vein ; but in many cases, as in C. concolor, B. Desv., it can be distinctly traced as an unsealed vein right to the root of the wing, and, in the majority of cases, can be so followed for a considerable distance, while it is not uncommon to find a short length of the vein, internal to the cross veins, provided with scales. From the hindmost of the three root-trunks there springs only a single scaled vein, the sixth longitudinal, which runs without branching to end in the internal margin of the wing beyond the middle. On either side of this, however, is an unsealed vein, one of which joins the tip of the hinder branch of the fifth longitudinal, and is spoken of by Mr. Austen as the sixth longitudinal (the sixth becoming his seventh), and the other being his eighth longitudinal.
As a rule, these unsealed veins are left unnoticed in descriptions and figures of mosquitoes.
We come now to the transverse veins or vemdce, of which there are four in the CuHcidce.
Between the costa and auxiliary, close to the root of the wing, is the humeral transverse ; and the spaces into which it subdivides the interval between those veins are known as the costal cells.
Between the second and third longitudinals lies the
16 GNATS OR MOSQUITOES — CHAPTER I supernumerary transverse vein, which is considered by some as merely the angulated origin of the third longitudinal. Doubtless in some cases, as in Mucidus, the third springs from the second longitudinal very far out, but in these cases the supernumerary is absent, and the middle transverse, w^hich m most mosquitoes connects the third and fourth longitudinals, spans the entire space between the second and fourth. The remaining cross vein, or posterior transverse, connects the fourth with the anterior branch of the fifth longitudinal.
The relative length and position of these three lastnamed cross veins is of great value in distinguishing species. The branched portions of the second and fourth longitudinal veins and their unbranched portions, outside the transverse veins, are often spoken of as the anterior and posterior foicrchettes and their stems, and the spaces enclosed within the forks are commonly called the fork-cells. The relative proportions of these are also valuable aids in classification. Some authors entirely eschew the use of numbers in describing the longitudinal veins, and employ in their stead certain special names.
Where such are used, the first is commonly called the "post-costal," the second the cubital, the third the submarginal, the fourth the marginal, the fifth the brachial, and the sixth the anal, while Mr. Austen's eighth longitudinal would be spoken of as the axillary. Ficalbi speaks of the third longitudinal vein as the *' vena interposita."
The names of the remaining spaces, or " cells," can best be followed by a careful study of fig. 4.
For the rest, the incisura axillaris, a retiring angle in the outline of the wing in its axillary border near the base, and the alula, a lobe appended to the wing between the axillary incision and its base, alone require special mention. The latter, however, should not be confused with the covering scale that lies above the halteres, as is a not uncommon mistake.
The legs of Diptera, like those of other Orders, consists of four principal parts, the hips or coxce, the thighs or femora,
POSITION AND TERMINOLOGY OF THE CULICID/E 17 the shanks or tihim, and the feet or tarsi. Of these, the Coxce consists of two joints, the smaller second joint being called the trochanter ; the femur and tibia each of a single joint ; and the feet generally of five joints, of which the first is sometimes called the metatarsus. At the tip of the last joint are two claws {imgues), and under each of them there is generally a membranous appendage called the pulvillus ; many families having, in addition, between the pulvilli, a third appendage of similar structure called the epipodium , while in other families this appendage is bristlelike or altogether wanting. These claws vary greatly in form in the Gidicidce, and afford valuable specific characters. Fig. 5— Leg of a Mosquito.
The only remaining point that requires notice is the meaning of the conventions that are adopted with respect to the names of species. Two names are always employed ; the first of these indicates the Genus, always given the complement of a capital initial ; the second the species, of which there may be any number in a genus, and, unless the name refers to a person or a place, commences with a small letter.
Like the French Eepubhc, the species is " one and indivisible." Varieties there may be, though the practice of making them is usually regarded with disfavour, except among horticulturists, so that to speak of "a species of pictus " is apt to raise a smile on the face of the non-medical naturahst, much as a slip by the latter, in the use of a 2
18 GNATS OR MOSQUITOES — CHAPTER I medical technicality, would amuse a medical man. Practically speaking, a third name, that of the authority who first described the species, is always added ; so that the system is really trinomial. Not unfrequently a species is described again and again by different naturalists before it is discovered that all are referring to one and the same animal ; and in such cases, however incomplete the description or inappropriate the name, the custom is to employ that adopted in the description which has the priority of date, and the names used in subsequent descriptions are spoken of as " synonyms," e.g., Mr. Theobald finds that the species originally described by Fabricus as C. fasciatus, and referred to in the first edition of this handbook as G. tceniatus, Meig., has been redescribed under no less than seventeen other names, all of which appear merely as "synonyms" in the present edition. If, however, through error of the original describer, or on account of subsequent rearrangement, the species is referred to a genus other than that used by the original authority, the name of the latter is placed after the specific name in brackets, e.g., Anopheles hifurcatus (L.), in which case the species was originally described by Linnseus before the genus Anojyheles was separated from Culex. I devote some space to these points, because the failure to adhere to these conventions is a frequent source of confusion.
19 CHAPTER II.
On Collecting, Preserving and Appliances for Observation. In his delightful " On the Prowl," our genial Anglo- Indian naturalist " E. H. A. " remarks : " The gun and net I would gladly leave behind, but they cannot altogether be dispensed with. Without a collection a man's knowledge of natural history becomes nebulous, and his pursuit of it dilettante. I am sorry it is so, for in spirit I am a Buddhist. But alas ! every Buddhist is not a Buddha ! " I am glad to say that "E. H. A." has lately decided to go on the "prowl" after Mosquitoes, for there is no one more likely to profitably pry out the secrets of their lives, and then, in quaintly humorous fashion, to hold them up to mingled execration and ridicule.
The training of medical men specially fits them for such work, and although its usefulness may not be at once apparent, sooner or later it becomes of value ; and the insignificant worm or insect whose habits of life we have traced, turns out perhaps to be the free stage of a parasite, dangerous to animals or man ; or a " pest " destroying crops of incalculable value. It is well nigh on a century ago since Fabricus, Wiedeman, Desvoidy and Meigen laid the foundation of our knowledge of the Mosquitoes, but to-day we reap the fruits of their patient labours, and if the last-named naturalist were alive to-day he could hardly fail to congratulate himself on the rare intuition which led him to denominate his new genus Anopheles by the Greek equivalent for noxious, for we now know that the insects of this genus are far more efficient checks on over population than all the armies of the world, armed though they be with all the products of modern science and ingenuity. Fragile
20 GNATS OR MOSQUITOES — CHAPTER II though they be, many of Meigen's " types of species of GuUcidoi are still preserved in very fair condition in the Jarden des Plantes, though some must be seventy or eighty years old. Few realise the enormous field of work open to the collector in all tropical climates, and to say the least, the pursuit forms a most fascinating hobby, and may be recommended as a far better insurance against boredom in old age than the most intricate knowledge of Hoyle and Cavendish.
As regards the Gulicidce an infinity of work remains to be done in identifying species with their larvae, in discovering their habits of life, food, and natural enemies, as well as in discovering how species tide over seasons unfavourable to their free multiplication, for it is only by work of this kind that we can hope to ultimately establish an exact and rational prophylaxis against malaria. Mosquitoes are rarely found far from water, as during the first two stages of their existence they are aquatic animals, and the imagines rarely fly far from the pool in which they lived as larva?.
The adult insects are found, not only in houses, but in groves, forests, and in any other situations where shade can be obtained during the day, while the larvae and pupae are common in all small collections of water where there is no strong current. In the hills they are common in pools in water-courses. They are to be found in all countries from the Tropics to the Polar regions, and some species have so wide a distribution as to rival that of man. In all countries the adults may be found at all seasons of the year, the maintenance of the species being mainly secured by the survival of impregnated females, which hide, and remain quiescent during seasons unfavourable to the well-being of the larvae. In searching for them in houses it should be remembered that it is in the darkest corners that they are most likely to be found, and that their favourite haunts are draperies, clothing hanging up, the corners of cupboards, behind furniture, and such like situations.
A very favourite hiding place, especially of Anopheles, is the under surface of tables, and indeed these Mosquitoes
COLLECTING, PRESEKVING AND APPLIANCES 21 seem to have a special liking for suspending themselves from the lower side of horizontal surfaces. For collecting in the open, the best time is the early dusk, but in shady gardens many species, notably Stegomyia fasciatiLS (Fabr.), and S. scutellaris (Walker), are active and vicious during the day, and in the autumn W\\\ even venture on short flights across patches of sunshine ; but I have never met with an Anopheles in the open during the day in India; though like other Mosquitoes, they will always leave the house if they can at sunset, and certain European species are undoubtedly diurnal.
Jungle and garden species, however, commonly harbour during the day in ditches and under bushes, so that it is necessary to disturb them by beating the bushes with a stick.
A number of pill boxes with glass bottoms should be taken, as the Mosquitoes must be brought home alive, or else portable setting materials must be carried, as delicate insects such as these can only be satisfactorily set immediately after killing.
In this sort of shikar nothing in the way of a call-bird is required, as the method of procedure resembles rather the plan of big-game shooting known as " sitting up over a kill," only the sportsman officiates as his own kill, " in addition to his other duties," as the Gazettes have it. All that is required is to sit moderately still and the Mosquitoes will come.
Mosquitoes may be captured : — (a) By slipping over them a small wide-mouthed bottle, as they sit on a wall or window, for which purpose a small "killing bottle" is best, provided that each insect can be set at once ; or the ingenious trap-bottle, devised by Ficalbi, may be used. This is constructed on the principle of the ordinary lobster pot, and consists of a wide-mouthed phial, through the cork of which is passed the tube of a small glass funnel, so as to project about finch into the interior of the bottle. The funnel should be somewhere about 2 ins. long, and about the same width at the rim, and the narrow part must be fairly wide (about i an inch), so that