Insects - Pests of Ornamental Trees, Shrubs and Flowers - page 15

Order DICTYOPTERA (cockroaches and mantids)

Family BLATTIDAE (cockroaches)

Periplaneta americana ( Linnaeus )
American cockroach
A relatively large (38-42 mm long), reddish-brown
cockroach; often present in heated greenhouses, where
it may cause damage to ornamentals and various other
plants. Unlike Blatta orientalis , the wings are fully
developed and reach beyond the tip of the abdomen.

Distinguished from mantises (family Mantidae) by the
unmodified front legs and broad pronotum which partly
or completely covers the head.

Blatta orientalis Linnaeus
Common cockroach
This generally common, well-known bakery and
warehouse insect often occurs in greenhouses,
destroying seeds and seedlings, and also causing
damage to the aerial parts of older plants. Individuals
hide by day but at night they become active and then
move rapidly over the floors and beds of infested
houses. Eggs are deposited in groups in purse-like
oothecae. These egg cases eventually split open to
release young nymphs, the incubation period of the
eggs lasting for one or more months according to
temperature. The nymphs feed for nine months or more
before becoming adults. Breeding is continuous under
suitable conditions. Adults are 20-30 mm long, rather
flattened, shiny blackish brown, with long, many-
segmented antennae, long legs and a pair of anal cerci;
wings are poorly developed.

Periplaneta australasiae ( Fabricius )
Australian cockroach
Minor infestations of this cockroach have also become
established in heated greenhouses in Europe.
Individuals are smaller than the previous species
(30-36 mm long), and adults and nymphs are more
extensively marked with yellow.

Pycnoscelus surinamensis ( Linnaeus )
Surinam cockroach
A typically parthenogenetic cockroach, unusual in
retaining its ootheca within a brood sac so that the eggs
hatch whilst still within the mother's body. Probably of
oriental origin but now cosmopolitan; in Europe
infestations occur widely in heated greenhouses, where
cultivated plants, including ornamentals, are damaged.
Adults (21-23 mm long) are dark brown, with paler
wings and a pale band along the front of the pronotum;
the wings are fully developed.

Blattella germanica (Linnaeus) ( 4 )
German cockroach
Infestations of this relatively small ( c . 12-14 mm long),
yellowish-brown cockroach are sometimes established
in heated greenhouses and hot-houses. In common with
other species, they feed at night and sometimes cause
damage to ornamental plants.

4

4 German cockroach ( Blattella germanica ).