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!
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.