Thelabrum.- The labrumis flat, hollow lobe of the head (fig.2 B, . Lm) flexibly suspended from the lower edge of the clypeus. The lower incisor end (inc) generally has several coarse teeth on its mesal edge, and on the same side near the base is a broad, differently developed molar region (mol) facing the opposite jaw.
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The labial muscles (19) of the lingual sclerites and the lateral frontal muscles (14) of the oral arms are reducers. We have already seen how food is ingested in the prestoma through the action of the maxillary lobes and mandibles.
THE ALIMENTARY CANAL
7 BITING AND FEVERING INSECTS— SNODGRASS 19 movement of the bubbles, but it is evident that some sucking mechanism carries them to the mouth. If the base of the hypopharynx is pressed against the inner wall of the clypeus, the concavity of the cytophore becomes a closed chamber and the cibarium can.
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THE BITING LICE AND BOOKLICE. ORDERS MALLOPHAGA AND CORRODENTIA
In the first group, the short antennae are usually hidden in grooves on the underside of the head (fig. Labium has a broad base on the back of the head (A, Lb), which distally bears a pair of small palpi (E) , Pip ) and two median lobes (Pgl).
24 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 104 sclerite gives attachment to a muscle arising on the laterodorsal wall
Returning now to the Mallophaga, we find a striking resemblance of their mouth-parts to those of the Corrodentia. This rod exactly corresponds to the free, rod-shaped lacinia of Corrodentia (Fig. 10 G, Lc); it has the same retractor muscle (32) arising from the head wall and angular fibers (41) arising from the ossicles.
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THE ELEPHANT LOUSE
From the tip of the beak a long, slender, tubular alimentary canal (B, jm) leads back to the broad part of the head, where it expands into a bulbous chamber (C, CbP) provided with an enormous bundle of dilator muscle fibers (5) arising on clypeal legion of the main wall. Its suction apparatus is essentially identical to piercing and sucking lice (Fig. 13D).
THE SUCKING LICE. ORDER ANOPLURA
The prestomum opens into a spacious preoral cavity within the head (Fig. 13D), the upper part of which extends directly into the chamber of the cibarial pump (CbP), while the lower part extends along the sac (Sac) almost to reaches the edge. back of the head, which contains the stylets (STL). The posterior extension of the stylet bag below the mouth of the cibarial pump produces a transverse suboral fold (D, sof), the upper wall of which is the bottom of the pump (CbP).
34 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. IO4 probably differs in different species of lice, since descriptions by
THE FLIES. ORDER DIPTERA
The Diptera are all sucking insects; none of them bite in the usual sense of the word, since in none the mandibles are jaw-like. Although the species of flies are numerous, most of them are completely harmless to us, and yet the order of the most dangerous includes disease and parasite vectors that attack humans, other mammals and birds. The Brachycera have short antennae, and the number of segments is generally small, but is variable.
MOSQUITOES. FAMILY CULICIDAE
The vertical bar of the frons is marked by an amedian groove continuous from the coronal sulcus (cs) that divides the vertex (Vx). At its base is attached a large muscle arising on the middle part of the clypeus (Fig. 17 D), and on each side one. The mosquito's mandibles are said to have only one muscle, called a retractor by Robinson (1939), which arises on the tentorium.
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NO. 7 BITING AND SUCKING INSECTS SNODGRASS 41 The elongate labium of the mosquito corresponds with the distal
42 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. IO4 The cibarial pump (antlia cibarialis) is an elongate capsule with
Spiere.-5, sibarial pump dilators; 6, 7, precerebral dilators of faringeal pump;8, postcerebral dorsal dilator of faringeal pump; II, lateral dilator of faringeal pump; 13, sibarial pump retractor; 14, protractor of cibarial.
44 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. IO4 other two lateroventral, which are flexibly hinged to each other along
NO. 7 BITING AND SUCKING INSECTS — SNODGRASS 45
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The ability of the stylet bundle to perform the movements described above may seem remarkable, but independent movements of the bundle. The digestive tract of the mosquito (Fig. 19A) begins with the entrance to the pharyngeal pump (PhP), the cibarial pump, as al-. The single ventral diverticulum is a large sac (A, vdv) that extends from a narrow neck far posteriorly into the ventral part of the abdomen.
48 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. IO4 turns backward into the abdomen, and beyond the third segment of
The other authors, on the contrary, claim that the action of the pump is a conditioned reflex, since they find that mosquitoes without a labium will not always feed. Diseases of which mosquitoes are known to be vectors, or have been shown to be possible vectors, include human malaria, avian malaria, yellow fever, dengue fever, human and equine encephalomyelitis. Malaria, caused by a blood-dwelling protozoan, Plasmodium, of which mosquitoes are essential intermediate hosts, is transmitted to humans by species of Anopheles mosquitoes; the avian form of the disease is carried by Culex and Aedes species.
50 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. IO4 The virus of equine encephalomyelitis, which in the United States
SAND FLIES. FAMILY PSYCHODIDAE
The back of the head (C), unlike that of the mosquito, is mostly non-sclerotized, there is an extensive. The theca of the broad, strong labium (C, The) bears a pair of soft labellum lobes at its end.
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The musculature of the mouthparts of Phlebotomus is fully described by Christophers, Shortt and Barraud (1926). With the penetration of the stylets into the wound, the labium is probably pushed up into the membranous back wall of the head. The mandibles overlap, the left side always on top of the right side, and in this position the height on the lower surface of.
56 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. IO4 the left mandible fits into the upper depression of the right (K)
BLACK FLIES. FAMILY SIMULIIDAE
7 SNODGRASS INSECTS AND ENTIRE INSECTS 57 the anterior part of the thorax strongly sunk, and the pendulous head, which hangs on the neck below the level of the body. At the back of the head (B) the walls of the skull join below the foramen of the neck (For) and separate the latter from a broad ventral plate (Pmt), which is probably the postmentum of the labium. Each mandible is articulated at its base on a short arm of the cranium (C, mda) and is equipped with strong abductor and adductor muscles (K).
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NET-WINGED MIDGES. FAMILY BLEPHAROCERATIDAE
HORSE FLIES. FAMILY TABANIDAE
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The horseflies' suction apparatus includes a highly developed cibarium pump and a pharyngeal pump. The pharyngeal pump of Tabanus is a suction cup held between the posterior cornua (J, y) of the cibarium pump. The blood is obviously sucked out of the cibarium pump and driven further into the esophagus.
SNIPE FLIES. FAMILY RHAGIONIDAE
The pharyngeal pump (J, PhP-a), however, is completely different from that of the blood-sucking Nematocera; this. The powerful proboscis of asilids protrudes menacingly from the lower part of the head (Fig. 27A). The hypopharyngeal groove is the first part of the alimentary canal (D, fc); further back, as Whitfield has shown, the function of translation is taken over by the labrum canal, which becomes a closed canal towards the mouth (E, fc).
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SPECIAL FEATURES OF THE CYCLORRHAPHA
The lower surfaces of the labella, as in the horseflies, are grooved transversely by canaliculi ("pseudotracheae") that serve as food conductors. Philacmatomyia crassirostris (Stein), a blood-sucking fly from Africa, showing the soft, protruding, strongly armed terminal lobe of the. To support the now unsupported clypeus against the pull of the pump's dilator muscles, the clypeal edges (G, cr) are extended inward as a pair of plates (H, Ipl) that unite with the pump's edges ( CbP).
72 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. IO4 The clypeal plate of the Cyclorrhapha, recognized as such by Patton
EYE GNATS. FAMILY CHLOROPIDAE
NO. 7 BITING AND SUCKING INSECTS — SNODGRASS 73
74 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. IO4 the bulbous base of the haustellum to be firmly braced against the
The Rhodesian form of the disease is transmitted by Glossina morsitans Westwood and G. Horn flies and house flies are similar to tsetse flies in the structure of their gills and biting method. The maxillary palpi of hornbills are long and surround the proboscis as in Glossinus; the palpi of houseflies are short and protrude straight from the rostrum.
LOUSE FLIES. FAMILY HIPPOBOSCIDAE
The eyes are large, the antennae (Ant) are exposed, but the rostrum is hidden by the retracted haustellum. A peculiarity of the Hippoboscidae is the retraction of the haustellum into a deep pouch in the ventral part of the head (Fig. Between the labrum and the bottom of the labial groove lies the hypopharynx (Hphy), which is crossed by the salivary duct (sc).
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THE FLEAS. ORDER SIPHONAPTERA
The common name of the flea order, Siphonaptera, refers to the fact that fleas are wingless sucking insects; another name for it. The ventral arch of the peristome is the edge of the hypostome, which forms the inferior wall of the head. The four-segmented palpus (F, Pip) arises within the median basal angle of the maxillary lobe and usually projects downward.
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Its dilator muscles (18) arise from a horizontal plate (d) above that which appears to spring from the base of the hypopharynx. In the case of fleas, the eggs of the tapeworm are ingested by the larval flea, which is not parasitic, and the larval worms pass through the pupa to the adult stage of the flea. In the digestive tract of the insect, the bacteria multiply in large numbers, and some of them are expelled.
90 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. IO4 in a virulent condition with the feces, but they do not invade the
NO. BITING AND SUCKING INSECTS SNODGRASS 91 particularly in warmer regions ; it occurs in most of the coastal
THE THRIPS. ORDER THYSANOPTERA
The beak is composed of the labrum in front (Lm), maxillae on the sides and labium behind (Lb). The space between the hypopharynx and the inner wall of the labrum is the food meatus (jm), which leads up into a strong suction pump (CbP) with its dilator muscles (5) arising on the extensive clypeal area of the head (Clp) . Between the base of the hypopharynx and the labium, the salivary duct opens into a narrow salivary pocket (Sh).
THE SUCKING BUGS. ORDER HEMIPTERA
The lever evidently belongs to the lacinia; in the fleas it is merely the angled basal part of the lacinia (fig.34 G), in the Corrodentiaa lever is not differentiated (fig. 10G). The connection of the stylet with the lever and the insertion of the stipital muscles on it in the fleas and thrips show that the lever is. The same maxillary structure will be found again in the Hemiptera, but in this order the stipital lobe has become united with the lateral wall of the head, and the maxillary palpus is depressed.
GENERAL STRUCTURE OF THE HEMIPTEROUS FEEDING APPARATUS The head of a cicada (fig. 37 A) is conical with the apex down-
This lobe actually corresponds to the maxillary lobe of the flea (Fig. MxL) and to the body of the maxilla in the resar (Fig. The lateral stylets (MdS) are extensions of the mandible, the middle pair (MxS ) belong to the maxillae, their basal parts are hidden in the sacs of the ventral wall of the head .Anterior to the hypopharynx is an opening, the alimentary meatus (fm), which leads into a large cavity which is the lumen of the suction pump.
96 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. IO4 of their adjacent margins that extend clear through the head; in
The cicada's suction pump is a large, capsule-like structure that stands almost vertically in the lower part of the head (fig. 37C, CbB). The compression stroke of the pump is the result of the elasticity of the front wall. Valves have been noted in some forms that monitor the entrance and exit ports of the pump.
100 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. IO4 only movements the stylets are capable of making are those of pro-
Directing downward from the edge of the anteclypeus is a broad triangular labrum (C, H, Lm) covering the base of the bill anteriorly. The mandibular stylets are much more slender than the maxillary stylets and lie against the posterior surfaces of the former (I). The relationship between the stylets and the hypopharynx and the feeding passage is the same as described in the cicada.
ASSASSIN BUGS. FAMILY REDUVIIDAE
Segment IO4 to the subterminal aperture of the fourth (E, a) and adheres Segment to the subterminal aperture of the fourth (E, a) and adheres to the puncture between the sensory apical lobes. A bed bug feeds only on the blood of vertebrates, but it can survive without food for a long time. Aclp, anteclypeus; CbP, Cibar pump; Clp, clypeus; E, compound eye; Lm, labrum; MxL, maxillary lobe; MxS, maxillary stylet; O, ocellus; Oe, esophagus; SIDct, salivary duct; SIO, salivary mouth; SIP, sputum disease; Stl, collection of stilettos.
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The digestion of hemoglobin in the digestive tract, and the distribution of its disintegration products in the body tissues of a reduviid and other blood-sucking insects, is discussed in a recent paper by Wigglesworth (1943).
A study of the behavior of the mouthparts of mosquitoes when taking blood from living tissue; together with some observations on the ingestion of microfilariae. Further observations on the anatomy and function of the proboscis of the blowfly, Calliphoraerythrocephala L. A comparative study of the structure of the head and mouthparts of the Hippoboscidae (Diptera Pupipara).
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