[Japanese name: Yotsumon-semaru-hiratamushi] (Figs 1 A, B, 2 and 3)
Identification. The examined larvae were collected with adults of P. scitus and there were no other adults of Psammoecus species. The identification was confirmed by rearing some of these larvae to adult stage. Last instar larva. Head capsule width: 0.59–0.67 mm (n= 8).
Body (Figs 1 A, 2 A). Elongate. Head reddish-brown basally, frontal arm white, antennae blackish, bases and apices of 2 nd and 3 rd antennomeres white, 1 st somewhat lightened. Thorax and abdomen blackish-brown, darker toward posterior apex, lightened around lateral, anterior and posterior margins of each segment, 10 th abdominal segment reddish-brown, lighter toward apex.
Head (Figs 2 A, 3 A–E). Transversely oblong. Frontal arms U-shaped (Fig. 3 A). Antennae elongate; 1 st antennomere stout; 2 nd antennomere less than three times longer than 1 st, maximum width near apex, sensorium around apex of inner margin comparatively long and thick; 3 rd antennomere less than three times longer than 1 st, very short fine seta on apex (Fig. 3 B). Mandibles triangular, with three closely spaced teeth on the apex of right mandible, with four closely spaced teeth on the apex of left mandible; a long triangular prostheca on inner margin of anterior 1 / 5, maximum width in basal half; molae on bases of inner margins with many small strong cuticular spines, base of inner margin of left mandible protruded with several fine cuticular spines (Fig. 3 C, D). Maxilla longitudinally oblong, stipes dorsally with many moderately dense small spines on middle, with four long teeth near apex on ventral, inner margin of mala with relatively thick and long setae in a longitudinal row, anterior three setae thick; maxillary palpus with three palpomeres, 1 st palpomere short, 2 nd about 2.5 times longer than 1 st, 3 rd about 1.5 times longer than 2 nd with several very small spines on apex (Fig. 3 E). Six stemmata on each side (Fig. 3 A).
Thorax and abdomen (Figs 2 A, 3 G). Shape easily deformed according to posture. Prothorax subquadrate; meso-, metathorax and 1 st to 4 th and 8 th abdominal segments relatively wide, 5 th to 7 th subquadrate, 9 th absent, 10 th elongate, posterior angles of 8 th protruding a little. A pair of long fine lateral setae and some medium length setae on lateral segments, it on 1 st comparatively short. Legs elongate; trochanter quadrate, with a few medium length setae; femur with a long seta and a few short to medium length setae very sparsely; tibiotarsus thin, some medium length and many short moderately dense setae; claw a little more than 0.5 times as long as tibiotarsus, with two short setae (Fig. 3 F).
Specimens examined. 8 exs. (including one slide-mounted).
Pupa. Body length: 2.30–2.58 mm (n= 6).
Body (Fig. 2 B, C). Moderately flattened. Surface white (immature) to yellowish-brown, antennae, anterior and lateral portions of pronotum, wing pads and lateral portions of abdomen somewhat darkened (Fig. 1 B).
Thorax (Fig. 2 B, C). Prothorax transversely oval, dorsal surface enlarged, a pair of oblong pits on anterior portion gradually shallower toward posterior portion, lateral portions with furrows, shallow furrow along the posterior margin, a small tooth on each anterolateral margin, lateral margins with three large teeth, posterior angles protruding a little. Mesothorax transversely oblong, with furrow along anterior margin, shallow longitudinal furrow at the middle extending to 6 th tergite, posterior portions near bases of each wing pad depressed, with several longitudinal furrows on each basal wing pad. Metathorax comparatively longitudinally large, surface uneven, furrow on middle anterior portion comparatively deep.
Abdomen (Fig. 2 B, C). First to 6 th abdominal segments transversely oblong, 7 th triangular, 8 th segment transverse, 9 th small; posterior angles of 3 rd to 6 th segments protruding a little, with several short teeth; anterior angles of 4 th to 7 th segments ventrally with sockets for teeth of immediately anterior segments (teeth of 3 rd and 6 th in Fig. 2 B fitting into sockets of segments immediately posterior). Large protuberance on each lateral portion of 2 nd to 7 th and 9 th segments; protuberance I on positioned posteriorly and triangular, II positioned mid-laterally, enlarged in apical half, apex pointed posterolaterally, III positioned anteriorly, II, IV and V similar in shape, positioned between anterior angles and mid-laterally, mostly enlarged, bases narrowed, apices pointed posterolaterally, VI positioned at anterior angles, mostly enlarged, apices pointed almost laterally, VII on bases of lateral portions, similar to shape of II and III. Eighth tergite with longitudinal ridge in the middle; middle of posterior margin and right posterolateral margin pointed. Ninth segment completely divided into tergite and sternite, sternite bilobed.
Specimens examined. 6 exs. (including one slide-mounted).
Biology. The larvae of this species were collected from dead leaves of Japanese pampas grass Miscanthus sinensis Andersson with their adults.
In the laboratory, we observed that the pupae fixed their body by attaching the apex of abdomen to dead leaves in the petri dish. The posterior three abdominal segments were covered with the exuvium of last instar larva. In particular, the posterior two abdominal segments were tightly enveloped with the exuvium of 10 th abdominal segment (Fig. 1 B). Surface of immature pupa was mostly white.