188 MISC. PUBLICATION 4 2 4, U. S. DEPT. OF AGRICULTURE 



ruptions at various points or the pores reduced in size ; trilocular pores in a 

 single row usually extending across interruption in row of 8-shaped pores and 

 around apex of abdomen between apical setae, rarely terminating with the 

 8-shaped pores, usually as numerous as corresponding 8-shaped pores near 

 posterior end and one and a half times as numerous as that elsewhere, but 

 present or absent, or reduced in number or size where 8-shaped pores are 

 missing or are reduced in size. 



Dorsal surface : Minute 8-shaped pores numerous ; disk pores sparse ; tubular 

 ducts 24 fi long. 



Ventral surface : Antenna a roughly circular area with 1-3 very small setae, 

 2 as long as, and 1 slightly shorter than, diameter of antenna ; beak with 2 pairs 

 of setae ; spiracle with bar very narrow, and atrium enlarged, bag-shaped, and 

 containing 12-16 quinquelocular pores, 10-20 similar pores extending to body 

 margin in a row varying from single to triple ; multilocular pores, with 8-10 

 loculi, in 3 complete rows, the posterior row usually with 4 pores and each of 

 others with 6-12, the total number usually 20-28; a group of 10-25 (usually 

 around 20) dark-rimmed 8-shaped pores each side of beak, and few or many 

 tending toward arrangement in transverse rows posterior to mouth parts ; sub- 

 marginal 8-shaped pores usually in a single row but sometimes crowded so that 

 the row appears more or less double in lateral area, terminating near anterior end 

 of interruption in marginal 8-shaped pores, nearly as numerous as corresponding 

 marginal 8-shaped pores ; submarginal setae in a complete row terminating 

 anterior to the penultimate pair of marginal 8-shaped pores ; 1 pair of setae in 

 each row of multilocular pores and 1 pair before the anterior row. 



Apex of abdomen: Setae, apical 8-10 n long, interapical (inside, or rarely out- 

 side, apical) 3 m long, outer ventral 2.5 /j. long; anal opening very inconspicuous, 

 elliptical, situated on dorsal surface anterior to bases of apical setae, its margin 

 membranous, sometimes an inconspicuous fold in derm extending from end of 

 opening to bases of apical setae ; anal tube very short, membranous ; anal ring a 

 sclerotized, semicircular band connecting bases of 2 short, sclerotized collars, a 

 seta 7-10 n long, and a pore sometimes outside seta, in each collar ; a circular 

 opening in curve of band between collars, the margin of this opening appearing 

 somewhat sclerotized in some specimens, hardly discernible in others ; ventral 

 surface of apex rugose. 



Larva. — Nearly elliptical, posterior end narrowed. 



Margin: With 28 8-shaped pores, axes of nearly all transverse or diagonal: a 

 pair of minute setae close to each of the posterior 3 pairs ; 3 pairs of setae 

 anteriorly. 



Dorsal surface : 8-shaped pores in a lateral row of 9 on each half of body, about 

 one-fourth smaller than marginal pores ; disk pores slightly nearer marginal 

 than dorsal 8-shaped pores. 



Ventral surface : Antennal setae, I, 1 ; IV, 1 ; V, ; VI, 3 long, 2 stout, 3 fairly 

 stout ; antennal bases one-half length of antenna apart ; beak setae, 2 pairs 

 apical, 1 pair median ; spiracle with 2 trilocular pores : leg setae, coxa 2, femur 1 

 on inner margin near base, tarsus 1 each on inner and outer margins; tibia one- 

 half as long as tarsus ; 9 pairs of submarginal 8-shaped pores : apparently 9 pairs 

 of submarginal minute setae, on abdomen and thorax, 1 pair of submarginal larger 

 setae at anterior end: 3 pairs of setae near antennae and mouth parts. 



Apex of abdomen : Setae, apical 28-30 /* long, interapical 7.2 /* long, rarely 1 

 minute seta entad of interapical on 1 half of specimen, outer ventral 2 fx long; 

 anal opening ventral, circular ; anal tube very short ; anal ring a sclerotized band 

 with 2 minute setae which are usually visible only when the circumference of 

 the ring is visible. 



Test of male. — Elliptical, 0.75 mm. long, 0.5 wide; slightly convex dorsally, flat 

 ventrally ; pale greenish yellow, transparent, thin ; marginal filaments whitish to 

 pale pinkish. 



Adult male. — 0.7 mm. long. 



Head: Antenna 9-segmented, formula (longest to shortest), III, IV, V, VI, 

 VII, IX, VIII, I, II; antennal setae, I, 1; II, III, IV, 6 or 7; V, VI, 15; 

 VII-IX, around 10, in addition VII and VIII each with 1 stout seta and IX with 

 2 stout and apparently 3 very long setae ; sclerotized bars not observed ; approxi- 

 mately 15 setae between ventral eyespots and antennae. 



Thorax: Greatly modified; wings absent; internal framework of thorax rep- 

 resented by a T-shaped bar and 2 stout, sclerotized, hornlike processes, without 

 a bar in center ; tibia very slightly shorter than tarsus. 



Abdomen : Very slender ; five segments each with a seta dorsally on lateral 

 margin, 4 segments each with a seta in ventral lateral area ; each lobe area with 



