Puss Moth Metamorphosis

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

Puss moth eggs (Cerura vinula) on aspen

Cluster of puss moth eggs (Cerura vinula) on underside of aspen leaf

12 June: Hatched Ova

Hatched eggs of puss moth larvae (Cerura vinula)

Hatched eggs of puss moth larvae (Cerura vinula), showing signs of early feeding activity nearby.

12 June: 1st Instar

The ‘puss’ moths look a lot more cat-like at this early stage in their development I reckon.

First instar puss moth larva (Cerura vinula) on aspen leaf

1st instar puss moth larva (Cerura vinula) on aspen leaf. The distinctive tail-like appendages are already present.

1st instar puss moth siblings (Cerura vinula) feeding on aspen

1st instar puss moth siblings (Cerura vinula) feeding on aspen

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.

Puss moth siblings sharing the same aspen leaf

Puss moth siblings sharing the same aspen leaf

Puss moth siblings on shared aspen leaf

The puss moth siblings were running out of space on their steadily consumed leaf and occasionally paused to whip their tails furiously at each other.

Second instar puss moth larva on aspen leaf

Close-up of 2nd instar puss moth. The jagged tentacles above the head are very prominent at this stage, unlike in the fully mature larva.

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.

Third instar puss moth larva resting on silk pad

3rd instar puss moth larva resting on silk pad

Third instar puss moth larva resting on silk pad on aspen leaf

The distinctive saddle patterning of the puss moth caterpillar is much more visible by this stage.

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.

4th instar puss moth on aspen leaf

4th instar puss moth clinging to wet aspen leaf. The hump on its back is now filling out.

4th instar puss moth larva

At this stage in its development the puss moth’s body has begun to envelop its head and the tentacles appear to have retracted.

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.

Fifth instar puss moth larva

5th instar puss moth larva. All the outlandish features of the mature larvae are now present, including the lurid pink face, flagellae and false eye spots.

Fifth instar puss moth larva detail showing extended pink flagellae

Detail showing extended pink flagellae. When threatened the puss moth extends these whip-like appendages from its tail end and waves them around crazily.

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!

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Amphibian Kama Sutra

Common toads in amplexus

Common toads (Bufo bufo) spawning

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.

Common toads in amplexus

Group of toads in amplexus

Common toads in amplexus

Spawning might look fun but can also be life-threatening!

Common toads in amplexus

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.

Common toad crossing track

This toad was late to the party, but managed to avoid oncoming traffic

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Harvest Mouse Survey

Harvest mouse at night

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 nest

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

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 in bag

Harvest mouse recovered from trap

Weighing harvest mouse

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.

Harvest mouse being marked

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 mouse in the hand

Harvest mice require very careful handling by trained experts

With thanks to Surrey Wildlife Trust staff and volunteers.

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Digger Wasp Hostage

Sand digger wasp with caterpillar

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 wasp with caterpillar prey

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!

Sand digger wasp excavating nest burrow

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:

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The Magnificent Puss Moth

Puss moth caterpillar

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 caterpillar grazing on aspen

Puss moth larvae feed on poplar, willow, or here on aspen

Colourful character

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.

Puss moth caterpillar

Head end of puss moth caterpillar

Self defence

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 tail

Puss moth caterpillar with extended ‘tails’

Puss moth caterpillar tail

‘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!

Winter retreat

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.

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Butterfly Conservation Moth Report

Butterfly Conservation: Moth Report 2013

Butterfly Conservation: Moth Report 2013

Butterfly Conservation used my image of a nocturnal moth trapping event to illustrate their latest report:

Unsurprisingly the report concludes that UK moth numbers are in decline, documenting a 40% drop in total abundance in the south of England over the last 40 years.

On the bright side many more moth species have colonised Britain in recent decades than have become extinct.

This photograph was taken at a recent moth trapping event on Chatley Heath organised by Surrey Wildlife Trust. The original image below:

Moth Trap Assembly

Skinner Trap on Surrey heathland at night

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Suburban Oak

Suburban Oak

The ancient Crouch Oak in Addlestone, Surrey, UK

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.

Night Oak

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.

Oak Urban Effects I

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:

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