Agriculture Reference
In-Depth Information
(b)
Fig. 220 Antennae of adult flea beetles: (a) genus
Phyllotreta;
(b) genus
Psylliodes.
Fig. 221
Large striped flea beetle,
Phyllotreta
nemorum
(xl8).
DESCRIPTION
Adult
1.8-2.4mm long, metallic greenish-black,
somewhat rounded in outline;
antennae
11-
segmented
(Fig. 220a)
(cf. cabbage stem flea bee-
tle,
Psylliodes chrysocephala,
p. 149), mainly
black, with the second and third segments red or
reddish;
legs
black.
Egg
0.3 mm long, oval,
yellowish-white, with dark plates and pinacula
on the thoracic and abdominal seg-
ments.
Larva
up to 6 mm long;
body
white and
slender;
head
black;
thoracic legs
very short.
soil, typically in batches of three or four. The
eggs hatch in 8-10 days, and the larvae immedi-
ately burrow into the leaves to feed. On suitable
hosts, they mine within the leaves, petioles and
stems for 2-3 weeks; they then enter the soil to
pupate in earthen cells. Adults appear about
2 weeks later, usually in July. The young adults
enter hibernation in September, hiding away in
debris and litter. There is just one generation
annually.
Phyllotreta nemorum
(L.)
Large striped flea beetle
DESCRIPTION
Adult
2.5-3.0mm long, black with a pair of
widely spaced, sinuous, yellow bands on the
elytra, the black area between them widening
both anteriorly and posteriorly
(Fig. 221);
tibiae
reddish-yellow (cf.
Phyllotreta undulata,
p. 148).
Egg
yellow, spherical.
Larva
up to
6mm
long;
body
elongate and yellowish, with
blackish plates on the thorax;
head
blackish.
This flea beetle is a common pest of vegetable
brassica crops, especially radish and turnip;
brassicaceous ornamentals, such as wallflower,
are also attacked. Adults cause a pitting of cotyle-
dons and leaves, and the larvae form small, pale,
linear to blister-like leaf mines that eventually
dry out. Attacks are most serious on young
plants, especially in hot, dry weather when
growth is retarded by lack of moisture. Larvae
are unable to penetrate into heavily waxed plants
such as cabbage, cauliflower, rape and swede.
Phyllotreta vittula
Redtenbacher
Barley flea beetle
BIOLOGY
Adults occur from April onwards, and eggs are
laid on the surface tissue of host plants or in the
Minor infestations of this flea beetle occur on
grasses and cereals, including sweet corn. Adults
graze the upper surface of the leaves, removing
