Friday, 24 June 2016

Midsummer and middling at Newhaven's Castle Hill Local Nature Reserve

Week 12 of the transect walking season

We have reached mid-summer and the season at Newhaven's Castle Hill LNR is moving on apace. The clifftops are heading into their peak flowering season: Common Bird's-foot Trefoil, Horseshoe Vetch and Sedum make shining fulvous and citrine splashes of colour on the cliffs and offer nectar to a thousand-and-one pollinating insects. The pollen-eating Swollen-thighed Beetle (Oedemera nobilis) can be found on bramble blossom, oxeye daisy and various umbellifers, the aggressive males bundling rivals off their territories. On the north slope haws are already forming where only weeks ago the trees were adorned in bridal white blossom.

The transect-walking season is also approaching its mid-point and we continue to feel a sense of disappointment that there are not more butterflies on the wing. The weather was not bad during today's walk with unbroken sunlight for the duration, but a fresh breeze was blowing in off the sea, sending most butterflies and moths to ground along the exposed cliffs. June is a mid-point for adult butterflies - the eye in the year's butterfly storm. The June Gap is a time when the first waves of emergent adults have passed over and when their offspring are feeding-up and spinning-up prior to taking to taking wing in the high summer sky. Few adult butterflies are seen during the June Gap.

The Large Skipper is one butterfly which bucks the trend. This is an insect of rough grassy places which feeds as a caterpillar on cock's-foot grass and is present in a single brood from late-May or June through to August. It is a conspicuous, territorial and pugnacious butterfly and it should reach its peak at Castle Hill in the next week or two. Meadow Browns are making a cautious start to their adult season and they will gradually increase over the next month before building towards late-summer abundance. The first brood of Speckled Woods is now declining and, although numbers never completely disappear throughout the season, we will need to wait for about six weeks to see the next spike in numbers. The leafy paths which criss-cross the north slope of the reserve provide the dappled shady habitat which makes this one of the commoner butterfly species here.

A male Cuckoo was seen flying near to the Lookout during the walk, preparing to make its return journey to sub-Saharan Africa. The season really is moving on.

Butterflies (5 species)
Large Skipper (Ochlodes sylvanus)  8
Speckled Wood (Pararge aegeria)  2
Meadow Brown (Maniola jurtina)  2
Holly Blue (Celastrina argiolus)  1
Common Blue (Polyommatus icarus)  3

Moths (7 species)
Narrow-bordered Five-spot Burnet (Zygaena lonicerae)  1
Common Nettle-tap (Anthophila fabriciana)  1
Diamond-back Moth (Plutella xylostella)  2
Swan-feather Dwarf (Elachista argentella)  1
Common Marble (Celypha lacunana)  2
Garden Grass-veneer (Chrysoteuchia culmella)  1
Cinnabar (Tyria jacobaeae)  1

Common Cuckoo (Cuculus canorus)  1

Large Skipper (Ochlodes sylvanus)

Oedemera nobilis - the Swollen-thighed (leaf) Beetle

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