NOTULAE ENTOMOLOGICAE - Helda

i:U) NOTULAE ENTOMOLOGICAE XUH, 1963
6. Discussion and conclusions
The rodent burrows in northernmost Lapland seem-from the microclimatic
point of view to be less favourable as a habitat for Diptera than those in
Southern Finland. In more superficial burrows (types 1 and 2) the summer
temperature shows considerable diurnal changes, the night minima remaining
rather low. In deeper burrows in shady places (type 3) the temperature is low
throughout the warm season. Nevertheless, the collecting results show that
the latter type of burrow is not avoided by Diptera and, on the contrary, the
samples from the few Norway Lemming burrows investigated were comparatively
rich. It is possible that the low temperature ( + 1° f-2°C) may increase
the efficiency of the Barber traps.
The fluctuations of the population size of Clethrionomys nifocanus and
Lemmus Icmmiis in Lapland are remarkable and show a characteristic cyclic
pattern (KAI