Harold Benjamin Fantham.

The animal parasites of man online

. (page 61 of 99)
Online LibraryHarold Benjamin FanthamThe animal parasites of man → online text (page 61 of 99)
Font size
QR-code for this ebook


576 THE ANIMAL PARASITES OF MAN

is covered with narrow curved golden-brown scales, the abdomen has basal pale
bands to the segments and the legs and proboscis are unhanded. The stem of the
first submarginal cell is always less than one-fifth the length of the cell. It lays its
eggs in rafts in water-butts, etc., and even in the foulest water. They are first
deposited in England in June and July, and again soon after hatching in August. In
some districts this gnat bites man viciously, in others not at all.

The common tropical gnat (Culex fatigans, Wied). This resembles the
European Culex pipiens, but can always be told by the stem of the first submarginal
cell always being much longer than it is in C. pipiens. This is one of the species
that has been proved to transmit filarias to man, etc. Varieties of it occur in almost
every country between 40 N. and S., having a very similar range to S. fasciata. In
all countries it appears to be connected with the transmission of Filaria bancrofti,
and it is also said to carry the micrococcus of dengue fever.



Genus. Melanoconion, Theobald.

" Mono. Culicid.," 1903, iii, p. 238 ; 1907, iv, p. 507 ; 1910, v, p. 455.

This genus is composed of eight species, most of which are small black gnats
which bite viciously and which occur in swamps and jungles. They can at once
be told from Culex by the veins of the wings having dense broadened scales on their
apical areas and along the upper costal border. The femora and apices of the tibiae
are swollen.

The black mosquito, Melanoconion atratus, Theoh. This small gnat is a very
troublesome pest in swamps in the West Indies. The female bites both by day and
by night, and the bite causes severe irritation. The larvae live in permanent ponds.
It is almost black in colour, but sometimes presents a dull coppery sheen ; each
segment has small lateral basal white spots. Length 2*5 to 3 mm.

It occurs in Para and British Guiana as well as in the West Indies.

Ordinary mosquito netting is no use for keeping off this pest.



Genus. Grabhamia, Theobald.

" Mono. Culicid.," 1903, iii, p. 243.; 1907, iv, p. 284 ; and 1910, v, p. 277.
Allied to Culex, but separated by the wings having short fork-cells, mottled scales,
the median ones thick and also some of the lateral ones short and broad ; the last
two joints of the male palps are very slightly swollen. The eggs are laid singly, not
in rafts, and the larvae have short, thick siphons. Ten species occur and are found
in Europe, North America, West Indies and Natal. G. dorsalis, Meigen, bites
severely in Europe. G. sollicitans, Walker, is a great scourge along the New Jersey
Coast and at Virginia summer resorts and in Florida. It breeds in brackish wate r
and is the most common mosquito of the Atlantic seaboard.



Genus. Pseudotaeniorhynchus, Theobald ;
Taeniorhynchus, Theobald, non-Arribalzaga.

Differs from the former in having the whole wing veins clothed with dense,
broadish elongated scales. They occur in South America (T. fasciolatus, Arri.), in
Africa (T. tenax, Theob.), in Europe (T. richardii, Ficalbi). The latter bites very
severely.



OTHER NEMATOCERA 577

Genus. Taeniorhynchus, Arribalzaga ; Mansonia, Blanchard ;
Panoplites, Theobald.

Comfit, rend. heb. Soc. Biol., 1901, iii, 37, p. 1046; "Mono. Culicid.,"
1901, ii, p. 173; and 1910, v, p. 446, Theobald.

A very marked genus, easily told by the broad asymmetrical wing scales. It
occurs in Africa (T. africana and T. major, Theob.) ; in Asia (T. it ni for mis, Theob. ;
T. annulipes, Walker, etc.) and in Australia (T. australiensis] ; in the Americas and
West Indies (T. titillans, Walker). The eggs (fig. 395, d) are peculiar in form and
are laid separately ; the larva has not been described ; the pupa has long curved
siphons. They mostly occur along rivers, in swamps and forests, and bite very
severely. They also enter houses (T. titillans]. T. uniforinis is most troublesome
during the rains. The saliva is strongly acid. Both these species carry the larvae of
Filaria bancrofti.

Genus. Chrysoconops, Goeldi.

" Os Mosq. no Para," 1905, p. 114, Goeldi; "Mono. Culicid., 1 ' 1910,
v P- 433> Theobald.

Bright yellow or yellow and purple mosquitoes, with rather dense wing scales.
Numerous species occur in Africa (aurites, annettii, fuscopennatus, etc.), others in
India, Australia and South America.

Low found filariae in the thoracic muscles ^fuscopennatus in Uganda.

Several of the dLdeomyina bite, especially the small Uranotcenias. They are all
sylvan species, seldom entering houses. They need net, therefore, be referred to here.

For full details of the Culicid genera and species the reader is referred to my
monograph 1 and other works mentioned below.

Other Nematocera.

Other nematocerous flies are midges, daddy-long-legs and sand-flies. The ones
which cause annoyance to man besides Culicidce are the following :

Sand-flies (Simulidce], certain midges (Chironoinida), and a few owl midges
(PsychodidcE).

The Nematocera have long thread-like jointed antennae and their pupae are, as a
rule, naked ; the larvae have a distinct head and can thus be told from the next
section (Brachycerd).

Family. Simulidae.

This family consists of a single genus, Simulium, Latreille, which Roubaud has
recently divided into two sub-genera called Pro-Simulium and Eu-Simulium. These
insects, which are frequently spoken of as sand-flies, are found in all parts of the
world; they are all small insects varying from 1*5 to 3 mm. The females are very
bloodthirsty, but the males appear to be incapable of sucking blood.

The head sunk under the humped thorax ; antennae short, straight ; palpi short

1 " A Monograph of the Culicida of the World, 51 5 vols. and atlas, 1901 to 1910, British
Museum (Nat. Hist.) ; and the following : Howaid, Dyar and Knab, "The Mosquitoes of
North and Central America and the West Indies," 1912; James and Listen, "The
Anophelinai of India," Leicester, 1908; "The Culicida of Malay," Inst. Med. Res., Fed.
Malay States, iii ; Ann. Trop. Med. and Par., papers by Nev\ stead and Carter; Mem. Inst.
Osivaldo Cruz, papers by Lulz, Neva, Chagas ; and the Bulletin of Entomological Research, etc.



578 THE ANIMAL PARASITES OF MAN

and broad, of four segments, bent ; wings broad and in some iridescent, legs stout.
The male has holoptic eyes, whilst in the female they are small and widely separate.
The sucking proboscis is short. The thorax and abdomen are clothed with short
hairs which may form spots and markings ; these are golden, silvery, grey, or brown-
ish. In the sub-genus Pro-Simulium the second segment of the hind tarsi in both
sexes is elongate, linear, and without a basal notch ; in Eu-Simulium it is short,
curved, and dorsally notched at the base.

Simulidce often occur in swarms, and attack not only man but cattle, horses,
and poultry. In some districts they are more annoying than mosquitoes.

Their life-cycle has been most completely worked out by King, in Africa.

The larvae and pupae occur in swiftly flowing water, by waterfalls, in rapids, etc.
The ova are laid in gelatinous masses on plants or rocks close to or overhanging the
water. The larva is cylindrical, enlarged posteriorly, where it is provided with a
sucker, by means of which it attaches itself to a rock, water weeds, debris, etc. ;
anteriorly it has a proleg close behind the head on the lower surface. The head is
dark and chitinous. The respiration takes place by means of branched tracheal gills
which protrude from the dorsal surface of the last body segment ; they are retractile.
The colour varies from deep green to yellow or almost black. Their food consists of
algae and other organisms in the water brought to their mouth by two fan-like organs
.placed on the head. The larvae can crawl from place to place by means of the
thoracic proleg ; they occur in masses, usually in a more or less erect attitude. A net-
work of threads is spun on their support, by means of which King tell us " they are
enabled to maintain their position against the strongest current ; frequently they will
leave their support and let themselves out into the stream anchored by threads of
silk and enabled by them to return."

When full fed the larva spins a pocket-shaped cocoon on the support, within
which it pupates. The pupa is motionless and has a pair of branched spiracles pro-
jecting from behind the head. When the adult emerges, a bubble of air collects
around it, and in this it floats to the surface and at once takes wing. The European
species take a month to complete larval life, a week being spent in the pupal stage.
The flies are most restless, and even when stationary continually move their legs
about like feelers. Sometimes the swarms consist entirely of females, sometimes
early in the season mostly of males.

The females pierce the skin of humans on tender spots, such as ears, the fore-
head, around the eyes and nose, and crawl into the cavities. They are quite harmless
at night, mainly attacking about sunrise and sunset. Some crawl up the arms and
legs and down the neck, and leave behind little red weals which itch intensely
(S. damnosum, Theob.), and blood may flow freely from the wounds.

The following are some of the worst species :

SimuUum columbaschensis, the " Kolumbatz fly," which abounds in the damp
marshy lands along the Danube, and is a great plague to man and beasts in Hungary,
and is also abundant in Austria and Moravia, and is most numerous after inunda-
tions from the Danube. They sometimes appear in such swarms that it is impossible
to breathe without getting them into one's month. There are instances of children
being killed by these flies when left on the ground by their mothers when working
in the fields.

S. damnosuni) Theob. This occurs throughout Equatorial Africa and is known
as the "jinja fly" in Uganda, the "fouron" in the French Congo, the "kilteb"
in the Sudan. It is a most vicious biter, and in some parts occurs in "belts";
Dr. Christy found one such extending from the shores of the Victoria Nyanza
rthwards along the right bank of the Nile for twelve or fifteen miles or more, and
perhaps three or four miles wide. In this area the flies swarm in millions at certain



CHIRONOMID^E 579

seasons, so much so that the natives have to leave their plantations. The bite
causes a weal, marked by a drop of blood.

S. griseicollis, Becker. The so-called " nimitti " occurs in Upper Egypt and
the Anglo-Egyptian Sudan. It lives near the river and is not found more than
half a mile from it. Human beings are bitten on the face and hands, animals in
the region of the pudenda.

S. latipes, Meigen. This is a European species, also found in Natal.

S. wellmanni, Roubaud. The " ohomono " of Angola, where it bites viciously
and is dreaded by the naked porters.

S. buissoni, Roubaud. Occurs in abundance in the Marquesas Islands. It has
been suggested that this species may help to propagate leprosy. 1

A large number of these insects have been described by Lutz in Brazil.' 2

A Simuliiun sp. (?) is very harmful to poultry in Cape Colony. 8

In America, Simulida are most annoying. One, S. meridionale, Riley, also
known as the turkey gnat in the Mississippi Valley, has been supposed to be the
carrier of chicken cholera ; anyhow, it has caused the death of thousands of chickens
and turkeys in Virginia annually. 4

In Mexico Townsend found a Simulium which was named S. occidentalism which
caused great annoyance to man, many people being so susceptible to them as to





FIG. 401. Wing of Simulium. FIG. 402. Wing of Chironomus.

preserve through the gnat season a chronic inflammation of the exposed parts of
face and neck, resulting from the repeated bites giving rise to sores. 5

Men and horses have been partially incapacitated by the bites of sand-flies or
Simulium in a Hampshire wood (Cantlie, Brit. Med. Journ., April 28, 1900,
v, No. 2,052, p. 1023).

Family. Chironomidae (Midges).

The Chironomidce or midges are not only frequently mistaken for mosquitoes,
but some are very annoying to man by biting him as mosquitoes do. They are
easily distinguished from true mosquitoes (Culicidcz] by the following characters :
(i) head small, often retracted under the cowl-like thorax ; (2) no scales to the wings
or body; and (3) the different arrangement of veins on the wings (fig. 402).

Two genera are important as annoying man, namely, Culicoides, Latreille, and
Johannseniella, Williston. The larvae of Chironomidcz are either aquatic, both
fresh water and marine, and help to make the former foul, 6 according to Slater, or
may, as in Ceratopogonince, live beneath the bark of trees, etc. The pupae are very
varied and also the life-histories of the different genera. 7 The blood-sucking habit
is confined to the sub-family Ceratopogonincc .

1 Bidl. du Mus. d^Hist. naf,, 1906, xii, p. 522.

' 2 Mem. Inst. Oswaldo Cruz, 1910, ii, fasc. 2, pp. 211-267.

:! C. Fuller, "A New Poultry Pest," 1899, Leaflet No. i, Dept. Agric.

4 Insect Life, 1888, i, p. 14. 5 Ibid., 1893, v P- 6l -

" Entomologist, 1879, p. 89. " Theobald, "An Account of British Flies," i, p. 172.



580 THE ANIMAL PARASITES OF MAN

Sub-family. Ceratopogoninae.

This sub-family of midges consists of very small species varying from i to
2 mm. in length ; the wings have darkened areas, and the second longitudinal vein
is wanting, and the first and third veins are stouter than the others and placed close
to the anterior margin, the fourth and fifth are forked ; the antennas in both male
and female are composed of fourteen segments, six or eight in the males bearing
long hairs.

The chief blood-sucking species belong to the genera Culicoides, Latreille,
and Johannseniella, Williston. The latter genus differs from the former in the
absence of an empodium or median appendage on the last segment of the tarsi.
The genus Ceratopogon, as restricted by Kieffer, is not supposed to take vertebrate
blood, but Austen has recently noticed that the type specimen of C. castaneus,
Walker, and a new species described by him, apparently have their bodies distended
with blood. The wings in the Ceratopogonino' are carried flat when at rest.




FIG. 403. A Ceratopogon, or midge. Greatly enlarged.

In spite of their small size the females are the most bloodthirsty and annoying of
all insects. The Culicoides, which are often called " sand-flies," bite during the day
and rarely at night. Usually they are most troublesome between 3 and 6 p.m.
They frequently attack in swarms, especially in the open, and owing to their minute
size can get through fine mosquito netting. Some of them produce a distinct " buzz J;
when on the wing. These insects are found in all parts of the world. No species
has been definitely connected with any disease, but Culicoides has been suspected of
carrying the germs of Delhi boil. The larvae of Culicoides are elongate in form and
have smooth bodies composed of thirteen segments including the head, which is
horny ; there is no proleg on the first segment as seen in Chironomus, and on the
anal segment are retractile gills. They are very active and live in the sap of various
trees which saturates diseased bark.

The pupae are smooth, but the abdominal segments bear a transverse row of
small spines. Austen describes a number of Culicoides and one Johannseniella and
three Ceratopogons from Africa, 1 and Lutz 2 a number of this sub-family from Brazil,

1 Bull, Ent. Res., 1912, iii, pp. 99-108.

Mem. Inst. Ostualdo Cruz, 1913, v , fasc. I, pp. 45-72, pis. 6-8: and 1914, vi, fasc. 2,
pp. 81-99.



PSYCHODIM: 581

including a new genus, Centrorhyncus. Another genus, Tersesthes, Townsend
(Centrotypus. Grass! ; Mycterotypus. Noe), also occurs in Brazil.

Culicoides ornatus, Taylor, is described from Townsville, Australia, found in
mangrove swamps. It is a very vicious biter and causes considerable irritation,
settling on hands and wrists (Taylor, Rep. Ent. Aust. Inst. Trop. Med. [1911],
1913, p. 24).



Family. Psychodidae (Owl Midges).

This family of diptera is of considerable importance, not only on account of the
blood-sucking habits of some species, but especially on account of one at least having
been proved to be the carrying agent of " papataci " fever, a three-day fever very
prevalent in Malta and several parts of Southern Europe in the autumn.

It is also possible that these small flies are connected with the formation of
41 Delhi boil," caused by a protozoan parasite.

Psychodidce are all very small flies, many of which have a moth-like appearance,
and owing to their fluffy nature are spoken of in Britain as "owl flies," sometimes
also as " window flies." Their bodies and wings are covered with hairs, densely in
some (sub-family Psychodina\ and in a few with patches of flat squamae. In the non-
blood-sucking Psychodince the wings are carried in a peculiar manner downwards
over the body, to a slight extent resembling the Hepialidce, or swift moths. The




FIG. 404. An owl midge, Phlebotojmis sp. Greatly enlarged.
(From Giles's "Gnats or Mosquitoes.")

wings may be ovoid or lanceolate, and have a marked venation as seen in the figure.
The proboscis is short and non-suctorial in the majority of genera, but in the sub-
family Phlebotomin<z it is elongated and hard. The antennas are long and of sixteen
segments, and bear whorls of fine hair.

There are two sub-families, Psychodince and Phlebotomince ; in the former the
mouth is not suctorial ; the female has a horny ovipositor and the second longitu-
dinal vein is branched at the root of the wing ; in the second sub-family the proboscis
may be formed for sucking, the female has no horny ovipositor, and the second long
vein has its first fork near the middle of the wing.

The sub-family Phlebolomina contains the genus Phlebotomus, which occurs in
South Europe, South Asia, Africa, North and South tropical America. They are
all small grey, brown, or dull yellow-coloured flies, and carry their wings when at rest
upwards like a butterfly. The proboscis is moderately long and the legs long and thin.

The females are most vicious blood-suckers, but in some species anyhow the



582 THE ANIMAL PARASITES OF MAN

males also bite (P. duboscii). They are mainly nocturnal feeders and hide away-
daring the day in any dark corners or crevices.

The life-cycle has been worked out by Newstead 1 and Grass! 9 in Europe, and
by Hewlett 3 in India.

The larvae have been found in crevices in rocks and caves, in dirty cellars, and
dark damp places containing rubbish, and are also said to live in crevices in the
walls of privies and cesspits.

The minute larva is very marked ; as figured by Newstead it has two long chaetse
projecting upwards, in some stages branched, in others simple, and on the seg-
ments a few blunt spine-like processes. The pupae are found in similar situations.
The ova are very minute, elongate, translucent white, and covered with a thin coating
of viscous matter when first laid ; soon after they become dark brown, shiny, with
long black wavy lines. Newstead found the incubation period in Malta to last for
about nine days in P.papatacii. Five species are known in Europe, five in Africa, 4
two in North America, and eight are described by Annandale 5 in the Oriental region.
Lutz and Neiva have described three species from Brazil 6 (P. longipalpis, inter-
inediits and squawiveniris},

Brachycera (Flies).

The antennae as a rule have three segments, and are usually shorter than the head.
The first segment of the antennas is frequently very small, and the third one is gener-
ally the largest, and sometimes possesses a terminal annulated bristle. The palpi have
from one to three segments ; the mandibles are covered by the labium. The three
thoracic rings are coalesced ; wings are almost always present, the posterior ones
being rudimentary and covered with a little scale. From the ova legless maggots
are hatched, which as a rule have not a distinct head, but occasionally possess
two claw-like booklets. These maggots live in decomposing organic matter ; they
rarely live in water and some of them are parasitic. They either become barrel-
shaped pupae within the last larval integument or, after casting it, are trans-
formed into naked pupae. The larvae of numerous Brachycera have been observed
in man, some in ulcers or on mucous membranes, others in the skin or in the
intestine, etc. In many cases the report only mentions the presence of the larvae of
flies ; in other cases the species has been determined ; whilst in still other cases the
corresponding adult creature is unknown. We must therefore confine ourselves to
describing the most common varieties.

Family. Phoridae.

These flies belong to the same division of Diptera, the Aschiza, as the family
SyrphidcE or " hover flies." They are all small insects with marked antennae and
wings ; the former have the third segment globular and enlarged, and thus hiding
the first two ; the wings are short and broad, the venation shows two short, thick,
long veins with four thin ones running out from them. The larvae normally live in
decaying animal and vegetable matter, but one species, Aphiochata ferniginea,
Brun., has been found as an intestinal parasite of man.

1 Bull. Ent. Res., 1911, ii, pt. 2, pp. 47-78.

"Ricerche sui Flebotomi," Mem. dell a Soc. ital. della Scienze, 1907, ser. 3, xiv,
PP- 353-394-

" Indian Sand-flies," 2nd. Med. Cong., 1909, sec. Ill, pp. 239-242.
1 Newstead : Btdl, Ent. Res., 1912, iii, pp. 361-367.
> Rec. Ind. Mus., v, pt. 3, Nos. 13 and 14.
" Mem. Imt. Oswaldo Cruz, 1912, iv, fasc. I, pp. 84-95.



SEPSIDJi, SYKPHID.E 583

Aphiochaeta ferruginea, Brim.

This small fly belonging to this family is of an orange-ochreous colour, the
upper part of the thorax tawny, and with dark bands on the abdomen, legs pale
yellow, the hind femora tipped with dark brown. It measures only 2 to 3 mm. in
length. This insect is shown by Austen to be widely distributed in the tropics,
being found in India, Burma, West Africa, and Central America. The larvae breed
in decaying animal matter, such as putrid meat, decomposing shell-fish, etc.

Heusner bred out sixty-three flies from larvae taken from an Indian's foot.

Baker (Proc. Burma Branch Brit. Med. Assoc., 1891, p. 11-16) found that
the maggots of this fly were passed per anum by a European at intervals during
a period of ten months. Baker found that the larvae fed on human faeces ; from
the egg stage to the deposition of eggs from the resultant brood of flies occupied
twenty-two days. He concludes that they are capable of propagating, and do
so while living within the human intestines. He also records the larvae in two
girls.

The larva does not seem to have been described, but Austen describes the pupa
(Trans. Soc. Trop. Med. and Hyg., iii, No. 5, p. 229).

Phora rufipes, Meig.

The larvae of the "hump-backed fly" live in rotting potatoes, mushrooms,
radishes, etc., and when accidentally introduced into the intestine of man can,
like other larvae, live there twenty-four hours and even more, and may set up serious
gastric disturbances.

P. rufipes is the same as P. pallipes, Latr.

Family. Sepsidae.

Small blackish flies, elongate, with abdomen narrowed at the base, thickened
and curved downwards towards the extremity. Larvae often found in decaying
vegetables, ham, cheese, etc. The larvae have the power of skipping ; conical in
form, pointed in front, truncated behind, about 5 mm. long, shiny and smooth, the
anal segment with fleshy protuberances. The genus Piophila has a short proboscis
and the cross-veins of the wings approximate.

Piophila casei, L.

Cheese flies. The larvae live in ripe cheese, with which they are sometimes
introduced into human beings (Meschede).

The larvae of the cheese flies (Piophila casei} may pass through the alimentary
canal of human beings alive, and have been occasionally referred to in cases of
internal myiasis. It also breeds in dead bodies in adipose tissue. Howard records
it on human excrement. It is thus possible that some of the recorded cases of this'
pest being passed alive may be due to eggs deposited on human faeces.

Family. Syrphidae (Hover and Drone Flies).

Amongst the large family of Syrphidce is found a section known as the Eristalince
or drone flies, whose curious long-tailed larvae are popularly called " rat-tail
larvae," on account of the end of the body being drawn out into a long telescopic tail
of two segments, at the end of which are placed the breathing pores. These larvae



584 THE ANIMAL PARASITES OF MAN

live in water, no matter how foul, and in liquid manure. They have occasionally
been obtained in foul drinking water by human beings and from eating watercress



Online LibraryHarold Benjamin FanthamThe animal parasites of man → online text (page 61 of 99)