Fróðskaparrit - 01.01.1993, Síða 76

80
PESTS RECORDED IN THE FAROE ISLANDS, 1986-1992
Fig. 19. Monthly distribution of species brought to
the Museum of Natural History, Tórshavn,
on average 30.
Mynd 19. Nøgdin av dýrum skrásett á Náttúrugripa-
savninum, í miðal 30 um mánaðin.
capital, Tórshavn, contains a third of the
total population, it is to be expected that it
also has the largest number of pests re-
corded (see Fig. 15, where no. l=Tórshavn
has by far the most records (177= 49.6%)).
When the percentage of inquiries on pests
is related to the percentage of Faroe Island-
ers living on the different islands (Fig 16),
the two curves follow each other closely.
The only exception concems no.l =
Streymoy, with the capital, where the per-
centage of pests exceeds the percentage of
Islanders. There are two reasons for this:
firstly, all supplies transported by ship
initially come to Tórshavn and secondly,
the fact that the Museum is situated in
Tórshavn, close to the finder.
Number of records per pest. In all, at least
77 different pest species have been record-
ed, 63 of which fewer than 5 times since
1983 (Fig. 17). The species most frequently
delivered to the Museum is the wood-bor-
ing beetle, Anobium punctatum with 52
(14.9%) records, followed by the Australi-
an spider beetle, Ptinus tectus (35 or 9.9%),
and the dark flour beetle, Tribolium des-
tructor (26 or 7.4%). It appears that many
different species occasionally arrive with
imported supplies, but they are unable to
establish themselves on the Faroe Islands.
As an example can be mentioned Sirex
and its parasite, Rhyssa (Fig. 18). The habi-
tat of Sirex is freshly felled timber. The
Faroese production of timber is sporadic
and the chance of importing timber con-
taining these Hymenopteran wasps is
small. This will result in only a few records.
Nevertheless, in the late 1980s, when a lot
of housing construction took place, Sirex
was brought to the Museum 5 times and its
parasite 3 times.
Number of animals throughout the year
A total of 357 specimens has been treated,
on average 30 specimens per month rang-
ing from 8 in December to 64 in October
(Fig. 19). This annual pattem has several
components. First of all, different species
have different seasonal rhythms. The sea-
son in which adult insects fly, mate, lay
eggs and fmd a place to spend the winter
will also be the peak period in which they
enter houses. Moreover, the seasonal activi-
ty of humans will also influence the likeli-
hood of discovering insects, for instance
when cleaning the house after Christmas,
or when cleaning the small sheds before the
freshly slaughtered lamb is hung to wind-
dry in October.