. Entomology for medical officers. Insect pests; Insects as carriers of disease. 40 ENTOMOLOGY FOR MEDICAL OFFICERS longitudinal is very short and takes off from the 2nd at a right angle; the 4th and Sth longitudinal veins both bifurcate; there is no posterior cross-vein, and so no discal " cell" ; both of the basal " cells" are long; there is no posterior basal cross-vein, and so no enclosed anal " ;. Pig. 7.—Wiag of Mosquito. It should be mentioned that in the wings of some flies faint traces of a longitudinal vein, or even of two may be seen behind the 6th
. Entomology for medical officers. Insect pests; Insects as carriers of disease. 40 ENTOMOLOGY FOR MEDICAL OFFICERS longitudinal is very short and takes off from the 2nd at a right angle; the 4th and Sth longitudinal veins both bifurcate; there is no posterior cross-vein, and so no discal " cell" ; both of the basal " cells" are long; there is no posterior basal cross-vein, and so no enclosed anal " ;. Pig. 7.—Wiag of Mosquito. It should be mentioned that in the wings of some flies faint traces of a longitudinal vein, or even of two may be seen behind the 6th. The abdomen is compact, but the segments are usually distinct. The number of visible segments varies from 4 to 8 or (rarely) 9. When the number of visible segments is small, it is generally the case that several inconspicuous posterior segments are present (and, perhaps, are introverted, or telescoped inwards) to form in the female an ovipositor, and in the male a part of the inseminating apparatus, or hypopygiuni (vtto = beneath; Truy?; = rump). Integument of Diptera.—The chitinous cuticle is often beset with hairs, or bristles, or sometimes with scales. In addition to this general investment, which may be either thick or sparse, there sometimes occur definitely placed bristles of larger size which have received special names according to their situation. Among these the following may be mentioned as their names, perhaps, are not self- explanatory : (12) vibrissa—these are two strong bristles sometimes found near the upper angles of the mouth-cavern, one on either side ; {b) dorso-central—these are bristles some- times inserted in rows in the field of the mesonotum; (c) sternopleural—these are large bristles sometimes found on the pleural plate that lies immediately above the middle legs ; (d) kypopleural^smzXlet bristles sometimes inserted in. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability
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