1887.) 239 



NOTE ON SOME BRITISH COCCID^. (No. 6). 

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



ASPIDIOTITS OSTBEJEFOEMIS. 

 Aspidiotus ostreafonnis, Curt., Gard. Chron., 1843, p. 805 and fig. 

 iVec Diaspis ostrecfformis, Sign., Ess. Cochin., p. 121, pi. v, fig. 4; nee D. ostreaeformis , 

 Comst., "Eeport," 1880, p. 311, pi. xv, fig. 4, and "Report," 1883, p. 94, 

 No. 65. ? Diaspis ostrecBformis, Goethe, Jahrbuch d. nass. Yer. fiir Natur- 

 kunde, 1884, p. 114, pi. i, fig. 1—5. 



$ scale round, 1 — •1'5 mm. in diameter, slightly convex, greyish-black ; exuvia3 

 nearly central, unicolorous, ashy-grey or usually dark yellow or rust colour ; the 

 surface rough or striate, often with a grey efllorescence (the largest were abnormally 

 swollen and parasitized). 



(J scale much smaller, oval ; exuviae more lateral. 



$ adult : the last abdominal segment with five groups of spinnerets, anterior 

 3 — 5, anterior-lateral each 6 — 9, posterior-lateral each 6 — 10 ; the margin with two 

 median lobes, followed on each side by two deep emarginations, between which is a 

 spinose hair, and but one further on towards the next segment, but these are not 

 always present or apparent. 



(J imago ochreous, thorax with a deep semi-oval depression, with a black trans- 

 verse streak at the base between the wings ; wings large, broad, whitish ; antenna 

 hairy, stout, almost as long as the body, apparently S-jointed, but having also two 

 very minute, intermediate, as adjuncts. 



Curtis described his Aspidiotus ostrecBformis thus : — 



" On the bark of a pear tree, covered with scurfy scales, exactly the colour of 

 the bark, mostly orbicular, but a few oval ; dark ashy-grey, a little convex, slightly 

 wrinkled, margin membranous and whitish, and between it and the centre a raised 

 semi-transparent spot of an ochreous or rusty colour ; when the scale is removed a 

 ' whitish or greyish spot is apparent upon the bark, on this the $ rests ; inside of 

 scale hollow like a shallow cup, at the top of whicli the yellowish horny spot very 

 distinct ; outer margin of scale broad, whitish, formed of the membrane which 

 attaches it to the bark. 



" The ? orbicular heart-shaped, fleshy, fat, shining, jellowish-white, with a few 

 short hairs scattered over the sides ; tail distinct, quite yellow, with a suture be- 

 neath ; neither legs nor anteunse, but on the under-side, a minute nipple, from which 

 issued the rostrum of considerable length. 



" Male under an oval scale ; bright ochreous ; head small, eyes black, antennae 

 nearly as long as the animal, hairy, stout, 8-jointed ; thorax large, ovate, collar 

 distinct, a black transverse stripe between the wings ; scutellum large, semi-ovate. 

 Wings ample, whitish, rounded ; halteres of two joints ending in a ciirved bristle." 



Siguoret places Aspidiotus ostrecpformis, Curtis, as a Diasjjis, 

 Baying (p. 122) :— 



" The scales of the $ are a little longer than those of the ? , brown, with the 

 exuviae on one side ; but afterwards (p. 441) he says this indication is erroneous, and 

 that " he has always found the $ scale very small, white, carinated, with the exuviae 

 at the extremity, as in all other scales of the group." 



Of the ? he says : — "There are five groups of spinnerets; median 10 — 12, 



