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secretion from their scent glands, and the cockroach is strongly
suspected of transmitting to man a number of pathogenic organisms
especially those of an enteric nature.
Cockroaches shun the light and are most active during the
night. Warmth, moisture, darkness and close proximity to food
supplies constitute favourable conditions for breeding.
As was to be expected most of the complaints received concerning
this pest came from bakehouses and the three large hospitals
in the Borough; very few originated from occupiers of dwelling
houses. The construction of such premises offers ideal breeding sites
in concealed and almost inaccessible places. Thorough investigation
and treatment with D.D.T. resulted in the infestations being considerably
reduced. In all, 125 treatments were effected.
Clover Mite. Complaints were received from tenants in blocks
of flats in various parts of the Borough concerning small red or
dark brown insects (Bryobia praetiosa) found moving over walls
and windows.
The clover or gooseberry mite is harmless to humans and to
household property. It is vegetarian feeding on a wide range of
plants and shrubs and, in some instances, on trees. During the
summer months of July and August the adult females leave their
feeding grounds to seek winter quarters, emerging the following
April to lay eggs on plants in the vicinity. It is during these periods
of migration that they cause concern when they move from their
natural environment into nearby buildings. Some infestations in
fact were reported from houses and flats where natural breeding
conditions were non-existent but where a recent laying of turfs had
occurred in the immediate neighbourhood. On 45 occasions,
spraying of interior and exterior surfaces with D.D.T. and Kerosene
produced satisfactory results. Such treatment also extended to the
spraying of trees and plants in close proximity to the source of
complaint. A miscible concentrate of malathion has been used
externally on a number of occasions with very good effect.
Wasps. Complaints received implicated three types, the Common,
the German and the Tree wasp. (Vespula vulgaris, V. germanica
and V. sylvestris).
Fear of the wasp is often misplaced for they rarely sting unless
they are roused or frightened and, contrary to popular belief, wasps
are not entirely harmful for in Spring and early Summer they feed
mainly on insects, many of which are themselves injurious. However,
after mid-summer their diet becomes more vegetarian and the
workers feed on ripening fruit and other sweet substances, thus
effecting serious damage in orchards, sugar warehouses, grain