Silba laevis


















Silba laevis
= Silba amita
Description: Size and colour similar to S. adipata McAlpine. Length 3.5-3.75 mm. Frons slightly depressed below ocellar triangle; no hairs arising dorsad of orbital bristle. Palpus unusually broad.
Male.—Head about one and one-fifth as wide as high (13.1: 10.5). Compound eye ostensibly bare. Frons as long from anterior ocellus to lunule as wide at former (7.0); distinctly narrower at lunule (6.0); with a slight depression in front of anterior ocellus which is deepest immediately below each orbital bristle. Orbital plate metallic blue; no setulae arising dorsad of orbital bristle. Postocellar bristles divergent; stronger than usual, almost as strong as dorsal bristle of second antennal segment. Lunule silvery-white pollinose; with four or five closely placed, relatively strong setulae on each side. Face lightly dusted with whitish pollen; horizontally convex, vertically concave; antennal groove fairly deep; entire face appearing depressed. Parafacial sub linear; silvery-white pollinose. Cheek, in lateral view, approximately two-thirds as wide as third antennal segment; in ventral view, as wide as the latter; with a single row of oral setulae, none distinctly stronger and vibrissa-like. Antennae brown; first and second segments paler at apices; third segment paler at inner base, almost three times as long as wide (8.0:2.8). Arista brown; yellowish on basal one-third; plumosity distinctly narrower than third antennal segment (2.2: 2.8). Palpus unusually broad; broader than third antennal segment (3.1: 2.8) and one-half as wide as long (3.1:6.0).
Thorax black with blue or bronzy-blue reflections. Mesonotum shining blue-black anteriorly becoming subshining bronzy-black posteriorly; hairs fine and decumbent; bristles strong. Scutellum fairly heavily coated with iridescent greenish or bronzy pollen; with five or six lateral and four apical setulae in addition to usual scutellar bristles. Mesopleuron and katepisternum as in following species; hairs somewhat stronger. With a single propleural and stigmatal bristle. Prosternum with several fine hairs on each side.
Wing rather strongly attenuated at apex; whitish hyaline; veins pale yellow. Calyptrae white, with concolorous fringes; margins pale yellow.
Legs and tarsi brownish-black. Abdomen black, with blue-black reflections; anterior tergites brownish pollinose in the middle.
Genitalia (Figs. 94, 97, 98) similar to that of S. adipata, but with a broader and shorter epandrium, a shorter aedeagus and a broader pregonite.
Female.- Similar to male, but with the usual sexual differences. Frons broader than long (4.5 : 3.5); distinctly narrower anteriorly than at posterior ocellus (4.0: 4.5). First and second antennal segments paler brown. Body somewhat shinier.
Ovipositor (Figs. 112, 113) slender. Apical segment elongate, with rather sharp apex; proximal dorsal and subapical ventral hairs approximately equal in length; about two-thirds as long as apical segment. Spermatheca (Fig.119) very similar to that of S. fraterna.
Transvaal: Barberton, 1 ~ (holotype), 2 9 (allotype and paratype), May 15, 8 and 22, respectively, 1913, H. K. Muwno. — Natal: 2 ,3~ (paratypes), Durban, Apr. 1, 1921, C. C. KE~r, aecount no. 807 [= reared from fruit of Momordica involuerata (Cucurb.)1. — Holotype, allotype and 2 paratypes in South African National Museum; 2 paratypes in Canadian National Collection.