May, 1888.] 265 



DESCRIPTION OF A NEW SPECIES OP ALEURODES. 

 BY J. W. DOUGLAS, F.E.S. 



Alkurodes RIBIUM. 

 Head, thorax and abdomen yellow ; antennse and legs pale ; wings milk-white, 

 immaculate. Eyes black, elongate, sub-reniform, ends broadly rounded, contracted 

 on both sides to the middle, and there crossed by a white farinaceous fillet, each 

 portion viewed from beneath with seven straight, transverse rows of distinct white 

 atoms. Antennae of seven joints ; 1st very short ; 2nd stout, bulbous, almost 

 obconic, the end hollowed out ; the otiiers thin ; 3rd longer than 2nd, cylindric ; 

 4tli to 6th somewhat shorter, sub-equal ; 7th longer, pointed. 



Expanse of wings, 2"60 — 2'75 mm. 



Larva short broad-oval, flat, shining, at first pale green, afterwards pale citron- 

 yellow, without hairs ; sides sloping upwards and 

 inwards from imeT' circumference to an oval ring, 

 smaller than but parallel to the circumference, the 

 edge of the ring set with a catenulated series of 

 small, obtuse elevations ; within the ring, on a 

 flattened surface, is a dim outline, in slight relief, of 

 the back of the insect beneath the integument, with 

 segmental indications, and on the median line of the 

 abdomen four or five small obtuse elevations ; the 

 sloped sides with close, delicate, transverse striee. 

 Length, 1"5, breadth, 1 mm. 



The imago, except as to the dotted eyes, as noted above (a struc- 

 ture that, although not recorded, may possibly exist in other species, 

 and be visible only in fresh examples), presents nothing remarkable, 

 the best specific characters, as usual in the genus, being demonstrated 

 in the larva. I believe that before winter the larvse had passed into 

 the pupa state, of which, as is well known there is, in this genus, 

 Bcarcely an outward and visible sign, but in this species, in the adult 

 larval state the outline of the insect below the integument is more 

 strongly defined in the thoracic region, and there are mostly dark, 

 suffused spots there and on the sides posteriorly, which character 

 disappears in the pupa. 



The number of joints in the antennae of the imago, even of the 

 same species, has been variously stated by different authors, of which 

 I subjoin some examples. 



A. proletella, Linn, {chelidovii, Latr.), Latreille (Gen. Crust, et Ins., iii, 1V4, 1, 

 and Regno Anim., iv, 188, pi. 69, fig. 16), six joints. Burmeistcr (Handb., ii, 1, p. 

 82), six joints, 2nd very long, 3 — 5 equal lengths; his figure pi. 2, fig. 7, represents 

 joint 1 as very short, 2 very long, nearly half the length of the antenna, 3 — 5 nearly 

 equal, 6 longer than 3. Heeger (Sitzungsber. d. k. k. Akad. d. Wissens., 1855, xviii, 

 35) remarks that Burmeister has probably overlooked the small, distinctly separated 



'A 



