Saturday, 25 November 2017

Life Cycle of the White Admiral

Now that autumn is moving towards winter, much of my time will be spent working in the wood. Rhododendron and bracken control is always on the agenda but coppicing, ride widening and wood thinning are essential in order to maximise potential breeding habitat for butterflies and moths.
 
Historically, most of our (now rare) woodland fritillary species would have been common in our wood. However, species such as the Pearl-bordered (Boloria euphrosyne), Small Pearl-bordered (Boloria selene) and Heath (Melitaea athalia) Fritillaries are highly unlikely to return naturally. I therefore focus my efforts on keeping the habitat right for species like the White Admiral (Limenitis camilla), which breeds in the wood in small numbers and also to encourage the Silver-washed Fritillary (Argynnis paphia) to increase its tiny population.
 
 
Life Cycle of the White Admiral (Limenitis camilla)
 
During the winter months, the White Admiral (L.camilla) hibernates as a tiny larva. It emerges from its hibernaculum in early spring and is fully grown by the end of May or early June. The pupa stage lasts for 2-3 weeks and the adult butterflies are usually on the wing from mid-June until the end of August. The ova are laid on honeysuckle leaves and the next generation of young larvae will start to build a new hibernaculum for the coming winter. 
 
 
A third instar larva has emerged from its hibernaculum and a recently shed skin can be seen just above and behind the larva. (20th April 2015)

 
 
A fourth instar larva on honeysuckle. (28th April 2017)


 
 
A fifth instar larva on a honeysuckle stem. (21st May 2017)


 
 
The same larva is suspended from a stem node of honeysuckle about 15 feet from the ground and in 90% shade. (27th May 2017)

 
 
Two hours later and the larva has shed its final skin. The pupal membrane is yet to harden.
 (27th May 2017)

 
 
The same pupa (dark form).  (29th May 2017)

 
 
 
 
The same pupa (dark form). The pupa has evolved to look like a crumpled honeysuckle leaf. The shadowy markings and reflective mirrors are clearly designed to break up its outline and make it less visible to predators. (4th June 2017)

 
 
Another final instar larva prepares to pupate beneath a honeysuckle leaf about 7 feet from the ground.
(31st May 2017)

 
 
The next day, the same larva has pupated. (1st June 2017)

 
 
The same pupa has adopted the more usual colour form. (2nd June 2017)

 
 
The same pupa. (4th June 2017)

 
 
The same pupa. (9th June 2017)

 
 
Sadly, the same pupa has been predated upon by a bird. Only the cremaster remains attached to the underside of the leaf. (11th June 2017)
 
 
 
The following three photographs are of a male White Admiral, freshly emerged from the dark form pupa. The left antenna is missing its tip and its left foreleg appears to be paralysed. After it had hardened its wings, I watched it fly up into the woodland canopy. (14th June 2017) 



 
 
The recovered pupa case shows that the pupa has sustained an injury or damage during its development. This has clearly interfered with the formation of the left antenna and is probably the cause of the paralysis in the left foreleg. (15th June 2017) 
 
 
 
My camera is not ideal for taking photographs of a pin-head sized ovum in subdued light but this image shows that the ovum is typically laid on the upper edge of a honeysuckle leaf.
(8th August 2017) 
 
 
 
The following photographs are of a second instar larva constructing its hibernaculum in preparation for the coming winter. The larva was about 6mm in length. (8th August 2017)
 
 

Tuesday, 7 November 2017

Battle for Survival

Soon, the focus of my attention will turn to scanning the horizon for raptors that overwinter across Pevensey Levels. However, while insects are still about, my gaze was firmly fixed on the field edges and hedgerows on Sunday, as Carol and I wandered around our usual circuit. Even into November, Common Darter (Sympetrum striolatum) were still numerous and a female Red Admiral (Vanessa atalanta) was busy laying eggs on nettle plants.
 
As we neared the end of our walk, I noticed a mini-drama taking place on the trunk of an oak tree, about 3 feet from the ground. A battle for survival was unfolding as we watched a Devil's Coach-horse Beetle (Ocypus olens) trying to subdue and dismember its prey; a species of Ground Beetle. The predator has to feed to survive and the prey species was desperately trying to escape its grasp. We watched for several minutes as the prey dragged the predator with it as it tried to release itself. The predator tenaciously hung on as it used its jaws rather like a tin-opener to cut through the wing case (elytron). The prey beetle seemed doomed but as the struggle continued, they both lost their footing and fell to the ground and were separated on impact. Battle was not rejoined and they went their separate ways. 
 
 
Devil's Coach-horse Beetle (Ocypus olens) (with prey)
 




 
 
 Just over a week ago, when I last put out the moth-trap, the catch was very small but did include two specimens of the scarce migrant moth Palpita vitrealis. This species has been arriving in southern England in good numbers in 2017.
 
 
Palpita vitrealis


 
 
Beaded Chestnut (Agrochola lychnidis)

 
 
Vapourer Moth (Orgyia antiqua) (male)


 
 

Wednesday, 18 October 2017

Season's Last Hurrah

The Clouded Yellow (Colias croceus) has been providing me with some end of season excitement on Pevensey Levels this week.
 
 Essentially a migrant species, it arrives in the UK from the near continent in varying numbers most years. It is usually first seen in May and can produce home grown broods during August and October, depending on weather conditions. Over the last few days, I have watched lots of males quartering clover rich pastures in search of freshly emerged females with which to mate. I have also seen three females of the pale helice form which can account for about 10% of the female population. This form does not occur in the male.
 
 
Clouded Yellow (Colias croceus) (roosting male)  
 
 
 
Clouded Yellow (C.croceus) (mating, with helice female)

 
 
Clouded Yellow (C.croceus) (freshly emerged male on clover)

 
 
Clouded Yellow (C.croceus) (males)


 
 
Clouded Yellow (C.croceus) (mating pair)

 
 
Clouded Yellow (C.croceus) (helice female)

 
 
Small Copper (Lycaena phlaeas) (female)

 
 
 
This Fen Raft Spider (Dolomedes plantarius) is the same female that was guarding her nursery web in my last post. Her spiderlings have now dispersed and she is enjoying some watery autumn sunshine.
 
Fen Raft Spider (Dolomedes plantarius) (female)  
 
 
 
 
Shaggy Inkcap (Coprinus comatus)
 
These three photographs are of the same fungus taken on three consecutive days.



 
 
Parasol Mushroom (Lepiota procera)

 

Sunday, 1 October 2017

Beautiful Peacock

Walking on Pevensey Levels during the last week, there has been a definite end-of-season feel. Hedges have been cut, pasture meadows have been mown and the maize crop has been harvested.
 
The third brood of Wall (Lasiommata megera) is just peaking and fresh looking Small Copper (Lycaena phlaeas), Red Admiral (Vanessa atalanta) and Peacock (Inachis io) are fairly numerous.
 
For me, the Peacock is our most beautiful butterfly; its rich velvety plum colour together with metallic blue eye-spots make a stunning combination. Sometimes, extra spots appear on the hind wings (aberration diophthalmica).
 
 
Peacock (Inachis io) (male)
 
 
 
Peacock (I.io) (male) (ab.diophthalmica)

 
 
Small Copper (Lycaena phlaeas) (female)

 
 
 
Pevensey Levels are very much an agricultural landscape, with sheep and cattle pastures dissected by ditches and water drains. At this time of year, many of the ditches become clogged with floating pennywort, an invasive water weed that needs to be raked out every winter. However, the pennywort does provide an excellent breeding habitat for the Fen Raft Spider (Dolomedes plantarius) and the cattle regularly graze upon it at the ditch edges.
 
The female plantarius in the photograph is guarding her nursery web near the middle of a ditch and out of reach of these curious cattle.
 
 
Fen Raft Spider (Dolomedes plantarius) (female at nursery web)

 
 
The season is also being reflected in the moth species that are starting to appear at the moth-trap in my Wealden garden. As well as some autumnal resident species, the star of the week was the appearance of a Delicate (Mythimna vitellina), a scarce annual migrant to the UK and a first record for my garden.
 
 
Delicate (Mythimna vitellina)


 
 
Autumnal Rustic (Eugnorisma glareosa)

 
 
Black Rustic (Aporophyla nigra)

 
 
Since recording my first Blue Underwing (Catocala fraxini) of the year a month ago, four more have appeared during the last week, three in one night. Whether they have emanated from a local breeding population or from a migration event is unclear but they have been appearing regularly at moth-traps across Sussex in recent weeks.
 
 
Blue Underwing (Catocala fraxini)
 
 
A second fraxini posed nicely for a photograph until the shutter was released, producing an image that will be familiar to many insect photographers!