Aphididao of Formosa. — 3. 71 



Winged form: Head and pronotum well defined; eyes slightly protuberant, 

 with the ocular tubercles distinct; antennae with the relative length of joints about 

 as follows: III-70, IV-25, V-30, VI-30; wing-pads well developed, pale yellow, 

 slightly dusky. 



Length of body-about 1.8 mm. Antehna-about 0.9 mm. 



The above descriptions were made from specimens collected on March 15 and 

 17, 1923, at Taihoku. 



The noteworthy points in the nymphal stage of this species arc as follows: 



Head and pronotum fused together except in the full-grown nymph of the 

 winged form. 



Eyes composed of 3 facets, but in the full-grown nymph of the winged form 

 true compound eyes begin to appear. 



Rostrum variable in length. 



The 3rd antennal joint of the winged form (tlie 3rd and 4th instars) is longer 

 compared with tliat of the wingless form. 



Head divided, though not so in the adult. 



Many viviparous females were observed on rodorarpuft on November 22, 

 1923, at Kankau, Koshun, Foi'mosa. 



Lachnus thujafoliae Theob. 



LncJmieUa thuja/oliae, Theobald, Bull. Entom. Research, IV, p. 335 

 (1914). 



Lachnus tlmjafoUae, Takahaslii, Aphididae of Formosa, part 1, p. 81 (1921 ) 

 and part 2, p. 135 (1923). 



Syn. Lachnus hiotac, van der Goot, Contrib. Fauna Indes. Necrland., 1, 

 3, p. 161 (1917). 



Nymph. 



The winged form shows four nymphal instars, but the wingless seems to have 



three instars. 



Key to instars. 



Wingless form. 

 ( 1 ) Antennae 4-jointed; cornicles situated on cones which are 



destitute of hairs The 1st instar. 



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



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



Antennae 6-jointed. The 3rd instar. 



