From September 1993 to September 1994 a programme of continuous pitfal
l trapping was undertaken by the Belgian Royal Institute of Natural Sc
ience on the Montagne St. Pierre. This hill is situated south of Maast
richt on the west bank of the River Meuse, partly in the Netherlands a
nd partly in Belgium. The study site is calcareous, and lies to the we
st of the village of Lanaye in Belgium, very close to the boundary of
different biogeographical zones. Trapping was undertaken in five areas
of open grassland and one area of former grassland substantially inva
ded by bushes in a successional stage towards deciduous woodland. The
traps were emptied every two weeks. Seventeen species of diplopods wer
e captured, twelve of which were julids. Julids comprised 93% of the i
ndividuals caught (4340 out of 4643 animals); the species Cylindroiulu
s caeruleocinctus (Wood, 1864) was predominant (3815 individuals, repr
esenting 82% of the captures). Activity was greatest in late winter an
d spring, with a subsidiary peak in autumn, and correlated reasonably
well with minimum temperature from the autumn until the spring. Few in
dividuals were captured during the summer. Some species were caught on
ly during limited periods of the year. In Cylindroiulus caeruleocinctu
s the proportions of males and females obtained in the traps varied co
nsiderably from season to season; there was a marked predominance of m
ales in the traps during the winter.