72 R- Takahashi 



Winged form. 

 ( 1 ) Antennae 4-iointed; cornicles situated on cones which lack hairs 



The Its instar. 



Antennae 5 or 6-jointed; cornicles situated on hairy cones (2) 



( 2 ) Antennae 5-iointed The 2nd instar. 



Antennae G-jointed (3) 



( 3 ) Wing-pads not well developed The 3rd instar. 



Wing-pads well developed The 4th instar. 



(The first instar) Body provided with many long hairs. Head divided, 



though not disiinctly so. Frontal tubercles lacking. Eyes scarcely protuberant, 

 witli no ocular tubercles. Antennae 4-jointed, hairy, not imbricated; the 3rd joint 

 with an apical sensorium which is very small, circular and not surrounded by liairs 

 as in the adult; the 4th almost as long as the basal two joints taken together; the 

 relative length of joints about as follows: III-50, IV-26. Eostrum reaching far 

 beyond the hind coxae. Cornicles situated on very short cones which are without 

 hairs. Legs furnished with many very long hairs; tibiae stouter than the antenna; 

 tarsi not imbricated, tlie 2nd joint almost 3.5 times as long as the 1st; hind tarsi a 

 little shorter than the 3rd antennal joint. Cauda very short, hairy, broadly rounded. 

 Length of body-about 1.2 mm. 



(The second instar) Differs from the 1st in the following characters: (1) 

 Body larger. (2) Eyes largei-, with the ocular tubercles beginning to be visible. 

 (3) Antennae 5-;ointGd; sensorium on the 4th joint larger; the relative lengtli of 

 joints about as follows: III-45, IV-20, V-30. (4) Hind tarsi almost as long as 

 the 3rd antennal joint. (5) Cornicles situated on hairy cones. 



(The third instar) Antennae 6-jointed; the i-elative length of joints about as 

 follows: in-45, IV-20, V-25, VI-30. Wing-pads beginning to appear. 



(The fourtli instar) Antennae 6-jointed; the relative length of joints about 

 as follows: in-65, IV--:6, V-32, VI-34. Wing-pads well developed. 



The meso-and metathoraces of the second instar of the winged form are very 

 slightly protruding on each side. 



Many wingless viviparous females and some nymphs of the winged form were 

 observed on Octover 10, 1923, at Taihoku. 



The cornicles of the first instar of Dilachnns and Pterochhrua are situated on 

 sliort cones whicii are almost destitute of hairs, as in this species, but those of the 

 second and the following instars are on hairy eonea as in the adult. 



