. A manual for the study of insects. Insects. DIPTERA. 421 hind wing; this is the alula (aru-la) or alulel (al'u-let). The alulae are well developed in the common House-fly. Each alula, in those species where the alulae are well developed, consists of two lobes which fold over each other when the wings are closed. The alulae are called the tegulcB by many writers on Diptera; but the term tegula jiiii (ni2+3 3114+5. VHa+IX Fig. 496.—Wing of Conors: ae^ axillary excision ; /, posterior lobe. was first used in insect anatomy for the cup-like scale which covers the base of the wing in certain inse
. A manual for the study of insects. Insects. DIPTERA. 421 hind wing; this is the alula (aru-la) or alulel (al'u-let). The alulae are well developed in the common House-fly. Each alula, in those species where the alulae are well developed, consists of two lobes which fold over each other when the wings are closed. The alulae are called the tegulcB by many writers on Diptera; but the term tegula jiiii (ni2+3 3114+5. VHa+IX Fig. 496.—Wing of Conors: ae^ axillary excision ; /, posterior lobe. was first used in insect anatomy for the cup-like scale which covers the base of the wing in certain insects, as most Hymenoptera, and should be restricted to that use. The terms alula and alulet are also often misapplied, being used to designate the posterior lobe of the wing. The plan of the venation of the wings can be easily learned by a study of the wing of Rhyphus (Fig. 497), which is very generalized in structure, except that vein III is only three-branched, while in cer- tain still more generalized forms it is $ve-branched (, Protoplasa, Fig. 504; and Psychoda, Fig. 500). In the figures of wings in this chapter both the veins and the cells are numbered. The numbers outside of the margin of the wing refer to the veins; those within, to the cells, except when otherwise indicated by a dotted line or by an arrow. It should be remembered that each cell bears the same num- ber as the vein that forms its front margin when the wings are spread. When a cell is divided by a cross-vein the two parts are numbered 1st and 2d. Thus in Rhyphus, cell V2 is divided, and the parts are designated as the ist cell Va and the 2d cell V2 (Fig. 497, ist Va, 2d V2). A cross-vein is marked cv. In the Diptera veins IV and VI are not developed. Vein I ex- tends along the costal margin of the wing; it usually ends somewhere near the apex of the wing; in Rhyphus it ends at the tip of vein (Fig. 497). In some families it extends entirely around the wing; it is then called the ambient vein.
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectinsects, bookyear1895
