1

w ta

_h

Hippoboscidae live on birds, and are apparently specially fond of the Swallow tribe. They are all winged, though in some species the wings are very small. The birdinfesting Hippoboscidae have been very little studied, and will probably form a distinct family; the antennae of Stenopteryx hirundinis are quite different from those of Hippobosca. The development is remarkable, and has been studied by Leuckart and by Pratt 2 in the case of Melophagus ovinus. The ovaries are peculiarly formed, and produce one large egg at a time; this passes into the dilated oviduct, and there goes through its full growth and a certain amount of development; it is then extruded, and undergoing little or no change of form becomes externally hardened by the excretion of chitin, passing thus into the condition of the Eumyiid pupa. Dufour thought that there is no larval stage in this Insect, but it is quite clear from later researches that he was wrong, and that a larval stage of a peculiar kind, but in some respects resembling that of the Eumyiid Muscidae, occurs. The larva has no true head, but the anterior part of the body is invaginated, and the most anterior part again protrudes in the invagination, so that two little passages appear on section (Fig. 246); the upper one leads to the stomach, which is of very large size. The tracheal system is peculiar; it is metapneustic, there being neither anterior nor lateral spiracles. Pratt says that there is at first a single pair of terminal spiracles, and subsequently three pairs, hence he considers that the terminal part of the body corresponds to three segments. This is however probably a mistaken view; it appears more probable that the socalled three pairs of stigmata really correspond with the complex

FIG. 246.-Diagrammatic section of the larva of Melophagus ovinus. (After Pratt.) a, mouth; b, suctorial pouch; c, imaginal disc for adult head; d, meso- and metanotal discs, e, anterior tracheal anastomosis; f, first muscular belt; g, transverse tracheal branch; h, the dorsal tracheal tube; i, sex-organ; k, Malpighian tube; 7, terminal part of intestine; m, terminal chamber of tracheal tube; n, stigmatic fossa; 0, terminal part of intestine; p, anus; q, anal disc; r, ventral tracheal tube; s, stomach; t, nervous system; u, discs for the three pairs of legs of the imago; 2, ventral pouch; u, pharynx; 2, suctorial lip.

1 Abh. Ges. Halle, iv. 1858, p. 145. 2 Arch. Naturgesch. lix. i. 1893, p. 151.

condition of the stigmata in the later instars of certain other Dipterous larvae. The Melophagus-larva is nourished by secretion from certain glands of the mother-fly; this is swallowed and the stomach is greatly distended by this milky fluid. Probably it was this condition that induced Dufour to suppose the larva to be only an embryo.

Some of the Hippoboscidae that live on birds take to the wing with great readiness, and it is probable that these birdparasites will prove more numerous than is at present suspected.

We may here notice an animal recently described by Dr. Adensamer and called Ascodipteron. He treats it as the female imago of a Pupiparous Dipteron. It was found buried in the skin of the wing of a bat of the genus Phyllorhina, in the Dutch East Indies, only one individual being known. It is entirely unsegmented, and externally without head. If Dr. Adensamer should prove to be correct in his surmise the creature can scarcely be inferior in interest to the Strepsiptera.

This consists only of a minute Insect The antennae are somewhat like those of

Fam. 41. Braulidae. that lives on bees.

FIG. 247.-Braula coeca.

are essentially similar.

the sheep-tick, though they are not so completely concealed in the cavities in which they are inserted. According to Müggenburg 2 a ptilinum exists, and he is also of opinion that although the parts of the mouth differ very much from those of Hippoboscidae they

x 18. (After Meinert.)
Lucas says that Braula specially affects

the thorax of the bee: Müggenburg, that it is fond of the

membranes between the bodyWhether this Insect is truly Boise states that a pupa is

queen-bee because of the exposed segments that exist in that sex. Pupiparous is unknown, though deposited in the cell of the bee by the side of the young larva of

1 SB. Ak. Wien. cv. 1896, Abtheil. i. p. 400.

2 Arch. Naturges. lviii. i. 1892, p. 287.

the bee, and appears as the perfect Insect in about twenty-one days. Müggenburg suggests that Braula may be oviparous, as he has never found a larva in the abdomen. Packard says that on the day the larva hatches from the egg it sheds its skin and turns to an oval puparium of a dark brown colour. The Insect is frequently though inappropriately called bee-louse; notwithstanding its name it is not quite blind, though the eyes are very imperfect.

Fam. 42. Streblidae. Winged; possessing halteres; the head small, narrow and free. These very rare Diptera are altogether problematic. According to Kolenati the larvae live in bats' excrement and the perfect Insects on the bats.1 If the former statement be correct the Insects can scarcely prove to be Pupipara. The wing-nervuration is, in the figures of the Russian author, quite different from that of Hippoboscidae. The Streblidae have been associated by some entomologists with Nycteribiidae, and by Williston with Hippoboscidae.

Family 43. Nycteribiidae.-The species of this family are

FIG. 248.-Nycteribia sp., from Xantharpyia straminea. Aden. A, Upper surface of female, with head in the position of repose; B, under surface of male.

× 12.

found on bats; they are apparently rare, and we have been able to examine only one species. The form is very peculiar, the 1 Horae Soc. ent. Ross. ii. 1863, p. 90.

Insects looking as if the upper were the under surface. They are wingless, with a narrow head, which reposes on the back of the thorax. The prothorax appears to be seated on the dorsum of the mesothorax. According to Müggenburg there is no trace of a ptilinum. A brief note on the metamorphosis1 by Baron Osten Sacken indicates that the mature larva differs from that of

FIG. 249. Anterior part of the body of Nycteribia sp., found on Xantharpyia straminea by Colonel Yerbury at Aden. A, Upper surface of female, with head extended; B, under surface of male, with head extended; C, claws of a foot.

Melophagus in the arrangement of the stigmata; they appear to be dorsal instead of terminal. There are apparently no characters of sufficient importance to justify the association of these Insects with the other divisions of Pupipara; the sole ground for this connection being the supposed nature of the life-history of the larva.

Sub-Order Aphaniptera or Siphonaptera (Fleas)

Fam. Pulicidae.-Wingless, with the body laterally compressed, so that the transverse diameter is small, the vertical one great. The head indistinctly separated from the body, small, with short thick antennae placed in depressions somewhat behind and above the unfaceted eyes. These are always minute, and sometimes wanting.

We all know that the Flea is so flat, or compressed sideways, that it

Mx.

(After Ritsema.)

direction. In other respects the FIG. 250.-Hystrichopsylla talpae. Britain. external anatomy of the flea shows several peculiarities, the morphological import of which has not yet been elucidated. The head is of very peculiar shape, small, with the antennae placed in an unusual position; the clypeus is said to A be entirely absent, the front legs are articulated in such a manner that they have a large additional basal piece-called by some anatomists the ischium and in consequence appear to be placed far forwards, looking as if they were attached to the head; the meso- and metathorax have certain flaps that have been considered to be homologues of wings; and the maxillary palpi are attached to the head in such a way that they appear to play the part of the antennae of other Insects (Fig. 250), and were actually considered to be the antennae by Linnaeus, as well as others; the mouthparts of a flea, l'er- parts themselves are differently constructed mipsylla alakurt from those of any other Insects.1 The maxillae 6. H. Unpaired and labium are considered to be not only present,

Мхр.

Lp.

FIG.

H. Md. Lp.

251. Mouth

pricking organ;

Md. mandible;

Lp. labial palp; but well developed, the former possessing palpi Me.maxilla; Mep. moderately well developed, while the labial maxillary palp. palps are very large and of highly peculiar (After Wagner.) form, being imperfectly transversely jointed. and acting as sheaths; the mandibles are present in the form of

1 The best general description of the external anatomy of the flea is to be found in Taschenberg, Die Flöhe, 1880. The morphology is better elucidated, though still incompletely, in Wagner's valuable "Aphanipterologische Studien," Horae Soc. ent. Ross. xxiii. 1889, pp. 199-260, 5 plates, and op. cit. xxxi. 1897, pp. 555-594, 3 plates. Cf. also N. C. Rothschild, Nov. Zool. v. 1898, pp. 533-544, 3 plates.