When it's an Early Spider Orchid in need of pollination.
Here in Sussex on the South Downs the orchid's only hope is a solitary Bee (andrena negroaena)
The Bee appears to try and mate with the flower* thinking it is perhaps another Bee and thus pollinating it. One might expect that from a Bee with a Bee Orchid but it's rather surprising that the spider like flower appears attractive to the Bee! I suspect scent plays a part and perhaps this is evolution at work and in fact the flower is changing it's appearance i.e. the individual specimens by chance looking more Bee like getting more attention and the more scary spider like variations not being pollinated? On Castle Hill near Brighton, where we were today, records show* that no more than 18% of the individual plants are successfully pollinated. Of course this may simply be due to the lack of Bees who's numbers fluctuate. Thankfully the same Bee species is the sole pollinator of these Orchids in their other strongholds Europe and the Mediterranean where the Bee population is more stable, so I'm told.
*photo curtesy of Wild Orchids of Sussex - David Lang