The fly orchid (Ophrys insectifera) is usually found on chalk and limestone soils in open deciduous woodland and scrub, but is also recorded from grassland and chalk-pits. It is rare in the UK and even at known locations can be difficult to spot.
Fly orchids in woodland clearing. Surrey, UK.
Fly orchids are in flower between May and June. At this time they attract male digger wasps (Argogorytes mystaceus) with a scent which closely resembles the female wasp’s pheromone.
Males attempt to copulate with the orchid and during this process pollinia become attached, which may be carried to the stigma of another flower, completing pollination.
Digger wasp attracted to fly orchid flower.
Male digger wasp pseudo-copulating with fly orchid.
Fly orchid pollinia attached to the head of male digger wasp.
I was finally lucky enough to observe and document this behaviour in the Surrey Hills earlier this year.
Experiment in environmental monitoring using a small consumer drone
For a few months now I’ve been experimenting with the (non-commercial) use of a small camera drone for environmental monitoring. The quality of the resulting images and the unique perspective it offers have been pleasantly surprising. Its potential applications at relatively low cost are impressive I think.
In late 2017 Surrey County Council, in collaboration with Surrey Wildlife Trust, decided that this Site of Special Scientific Interest (SSSI) would be a suitable venue to pilot their commercial felling operations in the county.
A felling licence issued by the Forestry Commission permitted them to extract 30% on 2 occasions over a 10 year period. Upon visiting the site however the impact at ground level looked far more extensive than I would have expected.
Concerned that contractors may have exceeded their remit and damaged the Scheduled Ancient Monument in the process I mapped an area to the north of the site, flying the drone in parallel lines at a height of 60 metres with the downward-facing camera set to take pictures at intervals every few seconds.
With the help of DroneDeploy’s internet cloud software I then stitched the resulting 139 overlapping images together to create an orthomosaic map layer.
Tracks left by the contractor’s heavy machinery can be seen running across the circular ‘henge-like’ earth bank feature.
To help peopIe unfamiliar with the site to visualise the monument in context I then generated a 3D model from the visual point data using DroneDeploy’s online competitor, Pix4D.
For terrain features and dense canopy this technique works well, but it struggles to accurately represent isolated trees and finer features. Without resorting to an expensive aerial LiDAR platform it would be difficult to achieve better results however.
The little drone done good on this occasion, and with minimal disturbance to this historically and environmentally sensitive site ironically.
I’ve photographed puss moth caterpillars (Cerura vinula) before, but this summer I wanted to follow them through all 5 stages, or ‘instars’, of their larval development.
Luckily I discovered a batch of recently laid puss moth eggs by searching the exact same aspen sapling chosen by another adult female the previous year.
6 June: Unhatched Ova
12 June: Hatched Ova
12 June: 1st Instar
The ‘puss’ moths look a lot more cat-like at this early stage in their development I reckon.
15 June: 2nd Instar
I’d received a shock on my visit the previous day when I found the caterpillars frozen rigid in position, with their backs arched and tails in the air. They looked decidedly dead and I thought they must have been parasitised. Today, however, they were re-animated once more.
24 June: 3rd Instar
9 days later, after vanishing for several days, the two siblings had relocated further up the branch they originally hatched on. Neither was particularly active in the midday heat.
28 June: 4th Instar
It lashed with rain on my next visit and the only visible puss moth was trying its hardest not to get pummeled off the leaf. Its silk pad lashed to the surface provides a firm anchor for feet to grasp.
9 July: 5th Instar
A further 11 days later I returned to find only one of the original 4 puss moth siblings remaining, now in its magnificent mature larval form.
To be continued…
Soon after reaching this mature larval stage the puss moth stops eating and leaves in search of a safe place to pupate. Its transformation into the furry white adult moth can then begin. Despite much searching I couldn’t locate any pupae. Next time maybe!
After emerging from hibernation in early spring, toads migrate back to their breeding ponds.
Males fight to secure mates and often outnumber the females at some sites. When this happens the female may be grasped by several males in a position known as ‘amplexus’, as they compete to be in the best position to fertilise her eggs.
Group of toads in amplexus
Spawning might look fun but can also be life-threatening!
Toad sex is apparently a moveable feast!
The common toad is widespread in Surrey, however populations appear to be declining. Where toad migration routes cross busy roads there can be many fatalities, and local conservation groups police ‘Toad Crossings’ at dusk to help them safely across.
This toad was late to the party, but managed to avoid oncoming traffic
Harvest mouse (Micromys minutus) captured on survey after dark
Last week I joined Surrey Wildlife Trust on a harvest mouse survey in wetland habitat beside the River Wey.
Harvest mice are tiny rodents 5cm in length. Their remarkable prehensile tails add an extra 6cm. They live in long tussocky grassland, reedbeds, hedgerows and around woodland edges, building a spherical nest of tightly woven grass, high up amongst the stems. We found several examples at this site:
Harvest mouse nests are woven from a mixture of living and cut grasses which provides excellent camouflage
Nests are the most obvious sign of harvest mouse activity since the animals are especially active around dawn and dusk and rarely spotted in the thick vegetation.
Dozens of rodent-friendly traps of different designs were set in the thick wetland reeds and grasses. Surrey Wildlife Trust staff and volunteers returned three times each day over the course of a week – at dawn, midday and dusk – to ensure that no trapped animals were left for any longer than necessary.
Rodent trap baited with peanut butter, bird seed and dried blowfly larvae
After retrieval from the trap harvest mice are transferred to a transparent bag for weighing and sexing:
Harvest mouse recovered from trap
Harvest mice weigh only 5g on average
Once the details of each rodent have been recorded a small patch of fur is trimmed to identify any animals which are subsequently re-captured.
Marking harvest mouse – a delicate operation!
The highest number of individuals captured was 12 one morning, making this the most abundant site for harvest mice in the county at present.
Harvest mice require very careful handling by trained experts
With thanks to Surrey Wildlife Trust staff and volunteers.
The sand digger wasp (Ammophila sabulosa) paralyses its prey
We encountered another variety of sand digger wasp on the heath recently – this time Ammophila sabulosa, which uses caterpillars to feed its larvae.
Sand digger wasps’ prey may be 10 times heavier than the wasp itself
Similarly to the spider-hunting wasp (Anoplius viaticus) it paralyses its victim with venom from its sting and buries it in a nest burrow. The caterpillar remains paralysed until the wasp larvae hatch out and eat it alive!
Female sand digger wasps excavate a short burrow in sand
The entire nest cycle from site location, through excavation and provisioning, to finally sealing the burrow, takes 8-10 hours to complete.
Many wasps have ingenious parasitic strategies, as these earlier blog posts illustrate:
The puss moth caterpillar’s ‘eyes’ are only for display
A colleague working for Surrey Wildlife Trust kindly guided me to the location of this wonderful puss moth caterpillar (Cerura vinula) yesterday. A pair of them were contentedly grazing on aspen leaves.
Puss moth larvae feed on poplar, willow, or here on aspen
In adult form the furry grey and white moth flies at night between the months of May and July. The larval form looks much more exotic. The gawdy pink ring around its face gives the puss moth a very distinctive appearance.
Head end of puss moth caterpillar
If disturbed the puss moth caterpillar extends two whip-like appendages from its tail end and flails them around to deter attackers. It’s a bizarre and unexpected thing to witness.
Puss moth caterpillar with extended ‘tails’
‘Tail’ detail of puss moth larva
It also has the ability to squirt formic acid from its thorax if further provoked, but I didn’t try that!
Shortly before pupation the caterpillar will change to a fetching shade of orange, and then again to purple.
It spins a cocoon of silk around itself and uses bits of tree bark as camouflage to stay hidden for the winter. The resulting cocoon is one of the strongest constructed by any UK moth.
I will have to return to see if I can find it in its various rainbow stages of development.
The Crouch Oak once marked the perimeter of Windsor Great Park and is thought to date from the 11th Century, making it in excess of 900 years old.
This ancient tree now looks a little incongruous as a modern residential estate has grown up around it.
The Crouch Oak at night with passing traffic
It’s interesting to compare depictions of this tree from the 19th Century and in 1904 as wooden fences are replaced with metal railings and a dusty track becomes a surfaced road. The oak also enjoyed an additional limb in those days.
In more recent times the Crouch Oak survived an arson attempt in 2007 and is now fitted with metal grilles across its hollow openings to prevent a repeat.
Metal grille stops burning objects being thrown inside
To see the Crouch Oak for yourself follow the map below to the bend in Crouch Oak Lane: