266
THE ESSEX NATURALIST
Other Bees
Colletes daviesana .......................... — — — — — —
C. marginata .............................. —
Apis mellifica .............................. —
Psithyrus campestris ....................... —
P. sylvestris Cuckoo bees ...... —
P. barbutellus .... ...................... —
Wasps
Vespula germanica .......................... — — — —
Mimesa bicolor (?M. equestris) .............. —
Sphex sabulosa (?Ammophila sabulosa) .... —
Oxybelus uniglumis ........................ — —
Crabro cribrarius .......................... — —
Ants
Lasius nigra ................................ — —
Ichneumons
Pimpla rufata (?Apechthis ruforta) ........ —
Amblyteles uniguttatus .................... —
No bumblebee colonies were found, although ants' nests were
quite abundant. The burrows of Colletes daviesana were very
frequent, particularly in the sand deposits near the bunkhouse. It
was apparent that this species had a definite preference for fine
sand as the small access holes and piles of sand, typical of C.
daviesana, were not found in the coarse gravel areas of the reserve.
Excavations by Bombus lapidarius were also found, although
these holes were only for hibernation purposes. Two such holes
were excavated and were found to be approximately four inches
long from the entrance to the base of the shaft. The occupant
of one of these holes, dug out from the north-facing bank of the
11/2 acre lake, was found to be carrying upwards of twenty mites,
later identified as Parasitica bomborum (Oudemans, 1902). These
mites have been studied by the author in a Bombus lapidarius
colony at Bishop's Stortford College. At the time of writing, the
exact nature of the relationship between P. bomborum and the
bumblebee colony is not completely understood. It is most prob-
able, however, that the relationship is of an advantageous nature
to the bumblebee colony up to a certain intensity of mite popula-
tion ; after that the mites are probably a disadvantage to the
colony. The other hibernating B. lapidarius was found on a
north-west facing bank dividing area 3 from the Saltings. There
were, however, no mites on this individual.
On a later visit to the Reserve on 7th October 1984, B.
lapidarius, B. lucorum and Vespa germanica were recorded in
hibernation in area 3 on a north-east facing bank.
During the 1963 visit foraging bees mostly visited the following
species: —
Rosebay Willow Herb (Chamaenerion angustifolium)
Ragwort (Senecio jacobea)
Spear Plume Thistle (Cirsium vulgare)