MEGARHINUS SEPTENTRIONALIS 949 



purple-scaled towards lateral margins ; first segment silvery-blue scaled ; seg- 

 ments with lateral patches of brassy scales which are broadest on sixth and 

 seventh segments ; claspers purple-scaled ; venter bright golden scaled, with a 

 rather broad steel-blue median stripe which is much narrowed on seventh seg- 

 ment ; eighth segment purple scaled ; lateral ciliation moderate, pale yellowish. 

 Wings narrow, smoky along outer margin; basal cross-vein oblique, reaching 

 fourth vein at, or beyond, anterior cross- vein. Legs very dark blue and purple ; 

 femora beneath brassy, knees white; front tibias with golden scales on outer 

 side ; middle tibiae with golden scales on inner side ; hind tibise with a few golden 

 scales on outer side ; middle tarsi with second and basal two-thirds of third seg- 

 ments silvery-white on outer side; hind tarsi with fourth segment entirely 

 brilliant white and base of fifth silvery white. Claw formula, 1.0-1.0-0.0. 



Length : Body 7 to 11 mm. ; wing 6 to 10 mm. 



Genitalia (plate 37, fig. 245) : Side-pieces over twice as long as wide, 

 sharply conically tapered ; a low lobe at base bearing three stout setae. Clasp- 

 filament slender, moderate, slightly thickened at base, bearing a long spine 

 before tip, and a few minute setae below. Harpes large, broad, with revolute 

 margins, tips bent outward, pointed and bearing a few minute setae. Harpa- 

 gones wanting. Unci contiguous at their tips, forming a long cone, the margins 

 revolute are serrate. 



Larva, Stage IV (see the figure of the entire larva, plate 82). Head sub- 

 quadrate, longer than wide, sides nearly straight, insertion of antennae rather 

 prominent; front margin deeply emarginate at middle, produced on each side 

 of it into a large prominent lobe. Antennae cylindrical, slender, rather long, 

 smooth; two separate hairs at outer third, followed by a short multiple tuft; 

 three small terminal digits and a long seta. Two pairs of single hairs behind 

 frontal lobes, a group of three in the sinus behind antennae, some small tufts 

 beyond middle of sides. Mouth-brushes inserted on frontal lobes, folded down- 

 ward and backward, composed of ten stout, curved, lamelliform blades with 

 slightly hooked cleft tips. Mental plate broadly triangular, emarginate at 

 apex for the space of the three middle teeth, seven teeth on each side, stout, 

 subequal; secondary plates thin, membranous, with apical fringes. Mandible 

 quadrangular, straight without, smooth ; two branched appendages at angle 

 before tip; an outer row of coarse cilia; terminal dentition of five teeth, very 

 large, ensiform, the third and fifth smaller; a large rounded projection basad 

 of teeth, within which arises a row of long subequal setae. Maxilla rounded 

 quadrangular, basal angle with a group of flattened appendages with recurved 

 tips ; inner angle with shorter filaments, a seta, and two papillae ; palpus nearly 

 divided by the suture, erect, columnar, flat at tip, smooth, with three rudi- 

 mentary terminal digits. Thorax rounded, about as wide as long; lateral hairs 

 short, very stout, heaviest ones spinulose. Abdomen stout, segments angled at 

 sides, anterior ones shorter ; hairs abundant but not long, all the lateral tufts 

 coarse, multiple to fifth segment, arising from large chitinous tubercles. 

 Tracheal tubes moderately broad, invisible in the larva, the skin darkly pig- 

 mented. Air-tube stout, conically tapered outwardly, about two and a half 

 times as long as wide; no pecten; a single tuft near base. A large plate on 

 sides of eighth segment with two stout spinulose hairs on its posterior margin. 

 Anal segment about as long as wide, ringed by the plate; dorsal tufts of two 

 long brushes on each side; a single spinulose lateral hair; ventral brush well 

 developed, of branched tufts, posterior one feathered; anal gills very short, 

 bud-shaped. 



The larvas live normally in water in hollow trees where other mosquito larvap 

 occur upon which they feed. More rarely they are found in artificial receptacles. 

 Specimens have been taken in water-filled rock-holes by Messrs. Pergande and 



