“Cocoxenus indagator, a ‘fruit fly’ that starves some solitary bees to death
You may see these little ‘fruit flies’ around your red mason bee nest boxes. This feeble flying insect is no fruit fly as a larva. It is a cleptoparasite . They are opportunists and literally hang around watching and waiting. They are looking to sneak into an empty cell, check it out to see if any pollen has been stored. If it has, she will quickly lay some eggs and leave pretty pronto before the host bee returns. The resulting larvae eat the pollen store and in many cases if there are simply too many of them, the bee larva will starve, usually to death. You can find up to ten larvae in one cell.”
Interesting to find it in a Blue mason bee nest
I have posted information on this bee before , I hadn’t seen one until the other week now I’m finding them everywhere. I was not expecting to see one here though as it is on the Fen side of Cambridge which is not the chalky grass lands they like , its more old railway embankment surrounded by miles of either rapeseed, broadbean or wheat fields. Anyway its a good sign and another record for the distribution map.
Probably the bee highlight of the year
The males of this species are among the first of the solitary bees to appear in the spring, with one exceptional record as early as late February. They are shortly followed by the distinctive females.
Status (in Britain only)
Classified as a Nationally Notable (Nb) species by Falk (1991).
Generally calcareous grassland and open deciduous woodland on chalk and limestone soils.
Univoltine; April to early July. The males are very short-lived in comparison with the females.
Females establish their nests in empty snail shells, including those of Helix pomatia, Cepaea nemoralis, C. hortensis and Monacha cantiana. Nests contain about four or five cells, depending on the size of shell used. Cell partitions and the closing plug consist of leaf mastic (i.e. masticated portions of green leaf). The space between the last cell partition and the closing plug is filled with a rubble containing very small snail shells and pieces of chalk, or soil. When the nest is completed the female covers the shell with a mound of dead grass stems, beech scales or leaf fragments (Perkins, 1884, 1891; G R Else, pers. obs.). The reason for this behaviour is not known, but it may camouflage the nest from possible parasites and predators at a time when it may be vulnerable to such attack….BWARS
A few of the bees seen on Fleam dyke this morning , many of the Andrena nigroaenea were stylopsed , ID’s in individual photos