Sept. 1,1925 
Identification of the Mealybug 
497 
THE DIFFERENTIATION OF THE SPECIES INVOLVED 
The key offered below, which will, it is hoped, facilitate the recog¬ 
nition of the species under discussion, is enlarged to include all of 
the species of mealybugs that have been recorded as occurring on. 
sugar cane, in the belief that its usefulness will be greatly increased 
thereby. These additional species, so far as the available records 
show, are Ferrisia virgata (Cockerell), Pseudococcus brevipes (Cock¬ 
erell) ( bromeliae of most authors), citri (Risso), saccharifoUi (Green), 
Ripersia sacchari (Green), and Trionymus sacchari (Cockerell). 
One record for Pseudococcus maritimus (Ehrhorn) is available, but 
here the species was taken in a greenhouse where the host was closely 
associated with, a number of other plants capable of serving as hosts 
for it, so it i$t not considered a sufficiently normal record to justify 
the inclusioh of the species in the key. Some other species of mealy¬ 
bugs have been reported from sugar cane in literature, but since the 
correctness of the identifications is not certain they are not included 
here. Usable descriptions and illustrations of the species Ferrisia 
virgata (Cockerell) (as Pseudococcus), Pseudococcus brevipes (Cock¬ 
erell) (as bromeliae), and Trionymus sacchari (Cockerell) (as Pseudo¬ 
coccus) have been given by the writer (16, p. 171-175); Ripersia 
sacchari was described and figured in 1900 by Green (4, V- 97-88), 
as was Pseudococcus saccharifoUi in 1908 (5, p. 23-24)- Unless other¬ 
wise indicated, authentic specimens of each species included in the 
key which follows have been examined. 
Key for separation of the species of mealybugs previously discussed 
a. Cerarian spines and indications of cerarii entirely wanting_ 
_ Ripersia sacchari Green 4 
aa. At least the apical abdominal pair of cerarian spines present, and that 
cerarius more or less distinctly developed. 
6. Body with numerous large tubular ducts, each opening in a cir¬ 
cular chitinized plate bearing setae, these ducts more or less 
clustered and in part replacing in position the anterior abdomi¬ 
nal cerarii; only the apical pair of abdominal cerarii devel¬ 
oped_ Ferrisia virgata (Cockerell) 
bb. Without such large ducts opening through plates. 
c. With only the apical cerarian spines present, these cerarii in¬ 
distinctly developed; margins of abdominal segments, 
anterior to apical, each bearing a long seta approximating 
the apical seta in length; body very stout at maturity- 
_ Trionymus sacchari (Cockerell) 
cc. With two or more apical pairs of cerarii developed; without 
large marginal setae anterior to the apical pair; body more 
elongate. 
d. No cerarian development on head; not more than four 
pairs of abdominal cerarii developed. 
e. Only the two posterior pairs of cerarii developed; 
multilocular disk pores scattered very sparsely 
over ventral surface of body, numerous around 
genital opening only - _ Trionymus danthoniae, new species. 
ee. With three or four posterior pairs of cerarii more or 
less developed; multilocular disk pores relatively 
very abundant over whole ventral surface and also 
sparingly present dorsally- 
-- Trionymus diminutus (Leonardi) 
* Included from a study of the original description only; no specimens examined. 
63338—25f-7 
