FIGURE 454. Oxyethira 

 tristella Klap. Pupal 

 case (after Klapalek) 



Full-grown larva. Length 4.0 mm. Resembling Ox. costalis but 

 the color is lighter; sclerites uniformly light, dark parts small. Head 

 oblong, 1.5 times as long as broad, yellowish white, without pattern; seta on 

 sensilla of antenna situated at /s of its length from the apex; middle frontal 

 seta of frontoclypeus thicker than the others; seta 9 long, straight and thin. 

 Upper and lower blades of left mandible with one 

 tooth; a narrow but deep notch at the lower blade near 

 this tooth; teeth more distinct and larger than in 

 Ox. costalis; two distal teeth on the right mandible; 

 end of the mandible slightly broadened. 



Thoracic tergites yellowish white; a narrow brown 

 border at the margin; angles chestnut brown; 

 posterior half of pronotum darker than anterior half, 

 brownish; thoracic setae as in Ox. costalis. Ratio 

 of length of legs 50.5:100:107.3; distal process of tibia 

 of forelegs with a row of short dark hairs on the 

 outside; midlegs and hind legs relatively slightly 

 shorter than in O x. c o s t a 1 i s; femora, tibiae and 

 tarsi of midlegs and hind legs darker than trochanter 

 and coxa; the claws are shorter relative to the tarsi 

 than in Ox. costalis: this ratio is 1:1.1 in 

 Ox. costalis, it is 1:1.3 (midleg) and 1:1.4 (hind leg) 

 in Ox. tristella; femora, tibiae and tarsi of legs 

 darker than trochanter and coxa. Abdomen as in 

 Ox. costalis. Sclerite of segment 9 yellowish brown; claw of holding 

 hooks with two dorsal denticles. 



Case resembling that of Ox. costalis; its broad part slightly concave 

 on the dorsal and ventral side; neck not as distinct as in O x. c o s t a 1 i s; 

 it resembles the narrow part of the larval case of Ox. distinctella 

 more closely. 



Pupa. Length of male pupae 2.46 mm, of female pupae 3.38 mm. 

 Antennae of male pupae with 35 segments (43 in Ox. c o s t al i s), reaching 

 the end of segment 6; antennae of female pupae with 25—26 segments, 

 reaching the 2nd abdominal segment. Unlike Ox. costalis and related 

 species, the labrum is trapezoidal, with rounded anterior margin, straight 

 sides and distinct anterior angles; 2 small anterior -angle setae present; 

 2 median setae on the posterior margin distinct; lateral setae not as long 

 as in other species; outer basal setae of different length, as in other species 

 of Oxyethira. Wing sheaths pointed, reaching the end of the abdomen in 

 female pupae and slightly further in male pupae. 



The oblong presegmental plates with a few posteriorly-curved denticles 

 (Klapalek (1887) mentions only 3 or 4 denticles), which form a short 

 350 pointed group (as in other species of Oxyethira); postsegmental plates 

 rounded, pale on segments 3 and 4, more distinct on segment 5. 



Pupal case (Figure 454) attached to the substrate by two pairs of 

 ligaments at the corners of the anterior margin; each ligament has a 

 separate small disk, one of them markedly smaller than the other; each side 

 of the neck with one ligament with a disk, which is slightly larger than the 

 anterior disks; posterior and often with 3 or 4 ligaments; membrane at 

 posterior margin of neck convex and slightly projecting. 



387 



