Heath Fritillary in Essex: a review of its status and a report of its second generation 125
Due to the strong emergence of the insects in high summer - coupled with fine and settled weather
through much of their flight period and beyond - I recall thinking at the time that the fritillaries may
again go on to produce a small second brood. However, I had no idea they were about to re-write the
accepted ecology of the species and respond to these conditions with something that is unprecedented
in the annals of British entomology!
First brood Heath fritillary counts at Hockley Woods SSSI by GL Bailey
Plot/ride |
number Date No seen Count time Weather/remarks
Plot 4 20-May 2 25mins Mostly rather overcast, but some very hazy sun. Quite
warm and humid
Plot 1 18-Jun 10 7mins Hot and sunny ~- 26C
Plot 2 18-Jun 12 4mins Hoi and sunny ~ 26C
Plot 4 18-Jun 117 25mins Hot and sunny ~ 26C
Plot 7 18-Jun 50 30mins Hot and sunny- 26C
PlotS 18-Jun 4 15mins Hot and sunny-26C
Pond area 18-Jun 12 8mins Hot and sunny - 26C
East ride 18-Jun 4 5mins Hot and sunny ~ 26C
Plot 10 18-Jun 3 l0mins Hot and sunny ~ 26C
The weather in August 1999 was generally rather unsettled, and I did not venture back to Hockley
Woods until the 28th, but I quickly found the fritillaries, significantly mostly within the new coppice
where the cow-wheat had sprouted in abundance on the bare ground. I eventually counted 20 of
them, with a large proportion ncctaring diligently on the plentiful supply of Rose-bay Willowherb.
They had undoubtedly already been flying for several days; eight weeks after completing their 'proper'
flight time, they had re-appeared in force. A return visit four days later revealed at least 30 displaying
in the morning sunshine - I now realised that something unique was unfolding around me, and being
eager to keep a careful track of the proceedings I came back on 2nd September, a sunny and very
warm day. The new generation of fritillaries was emerging in strength, and indicative of the many
mint-condition insects was a male still drying its wings and passing meconium, the pink fluid excreted
immediately after hatching from the pupa. The butterflies revelled in the ideal weather, and apart
from a mating pair, many were nectaring wherever they could. As well as the Willowherb, sustenance
was provided by Common Cat's-ear, Golden-rod and, most notably, by a doormat-sized patch of
Bistort that seemed irresistible to them: up to ten individuals were to be observed eagerly imbibing
from the flowers.
The unseasonal heat helped to maintain the momentum, and by 5th September Heath Fritillaries were
virtually the only butterflies to be seen in the wood, save for a few Speckled W7oods, Commas, Red
Admirals and various 'whites'. The temperature climbed to 28 C and the insects seemed to be
everywhere, spilling out to all areas of suitable habitat and feeding from an ever-widening array of
flowers - these now included Water Mint, Creeping Thistle and Common Fleabane close to the
Essex Naturalist (New Series) 17 (2000)