COMMON NAME: nigra scale
FIELD DESCRIPTION: Adult females
elongate-oval, somewhat narrowed in front,
moderately convex or flat, and sometimes hump-
backed at middle (Fig. 53). Length 3.5-4.0 mm.
Unsclerotized females opaque white; brown to
shiny black in sclerotized females. Dorsal surface
smooth or slightly wrinkled transversely.
DESCRIPTION: (Fig. 54) Adult females may
reach 5.0 mm in length, usually less (Ferris in
Zimmerman 1948). DoRsuM-Derm heavily
sclerotized in old females, with closely set
polygonal cell-like reticulations (Fig. 54, E).
Dorsal setae (Fig. 54, A) cylindrical or apices
swollen. Submarginal tubercles (Fig. 54, B)
variable in number. Combined anal plates
quadrate (Fig. 54, C). Few discoidal pores (Fig.
54, D) anterior of anal plates. VENTER-Anten-
nae well developed, 8-segmented. Tubular ducts
(Fig. 54, I) around submargin, absent from me-
dian region. Multilocular pores (Fig. 54, J) most
numerous around vulva with few on each ab-
dominal segment. Quinquelocular pores in
spiracular furrows. MARGIN-Marginal setae
(Fig. 54, K) stout with apex flattened, expanded,
clavate, or variously fimbriate. Spiracular setae
(Fig. 54, G) in groups of 3, median seta 2.5 to 3X
longer than laterals.
DISTRIBUTION: Map XX. AL, CA, DC, KS,
LA, MD, MO, NY, OH, OK, PA, TX, VA.
Foreign: Cosmopolitan.
BIOLOGY: Nigra scale has one generation per
year outdoors in California. Eggs were laid over
a very long period of time, from mid-May to
February (Smith 1944). Reproduction is by par-
thenogenesis. They feed on leaves, twigs,
branches, and fruits. The life cycle is very similar
under Florida conditions.

ECONOMIC IMPORTANCE: A pest of many
ornamental plants in tropical countries. In the
U. S., it is usually not a serious pest, but Merrill
(1953) reported nigra scale as an occasional
economic pest on hibiscus in Florida.
NATURAL ENEMIES: Some of the parasites
listed in Peck (1963) and Krombein et al. (1979)
are as follow: Chartocerus fasciatus (Girault),
TX; Coccophagus cowperi Girault, TX; C.
lycimnia Walker, cosmopolitan; C. ochraceus
Howard, TX; Lecaniobius capitatus Gahan, TX;
L. cockerellii Ashmead, FL; Scutellista cyanea
Motschulsky, cosmopolitan. In southern Califor-
nia, Metaphycus helvolus (Compere) has effec-
tively controlled P. nigra (Bartlett in Clausen ed.
1978).


REMARKS: In the field nigra scale may be con-
fused with the black scales (Saissetia spp.), but
the dorsal surface is much smoother and the
shape is more elongate in nigra scale than in any
of the black scales. Specimens mounted on a
microscope slide can be separated from black
scales because of the distinctive dorsal setae, dor-
sal reticulations, and lack of discal setae on the
anal plates of nigra scale.
MATERIAL STUDIED: FLORIDA; Apopka,
1(1), Monstera deliciosa, 8-III-1979, D. Rem-
ington; Groveland, 1(1), Hibiscus sp.,
23-VI-1970, W. P. Henderson; High Point, 1(1),
Homalocladium platycladum, 17-XI-1978, P.
Pullara; Lake City, 1(1), Pilea cadierei,
6-X-1970, H. W. Collins; Miami, 1(1), Aralia
elegantissima, 8-II-1972, F. J. McHenry; Pom-
pano, 1(1), Ficus sp., 7-III-1977, R. Schimmel;
Seffner, 1(1), Hibiscus sp., 23-II-1970, E. R.
Simmons; Seffner, 1(1), Hibiscus sp.,
18-VIII-1971, D. A. Vaughan.


Map XX. Distribution of Parasaissetia nigra.


Genus PARTHENOLECANIUM Sulc, 1908

TYPE SPECIES: Lecanium corni Bouch6, 1844.
DESCRIPTION: Body of adult female usually
strongly convex, naked, with a thin flaky wax, or
with powdery pubescence. Derm becoming