Hylands - Notable Species
Trocheta subviridis Dutrochet Hirudinea : Erpobdellidae
The spectacularly revolting Dutrochet's Land Leech is probably the largest invertebrate to occur in
Hylands Park. Although difficult to measure, adults can be as much as 9ins (23cms) long when
fully extended. At Hylands, it only seems to occur in the ha-ha ditch. Every year around about
March time, the accumulations of fallen leaves from the previous autumn are removed revealing
the presence of this species. It occurs between the irregular (sometimes broken) base of the ha-ha
ditch and the bottom of the leaf pile and it seems to tolerate quite high levels of organic decay here.
Over a period of three years I counted the numbers of leeches present and found the following:
2001 11 March 22nd
2002 16 April 11th (including 3 juveniles)
2003 63 March 26th (including 5 juveniles)
The 2003 count was possibly as a result of 'getting one's eye in', as they are not always easy to see
in the decaying leaf debris at the bottom of the ditch. The leeches were carefully placed in or near
water in the cleared areas and covered with wet leaves as we worked along the ditch; inevitably
some must get discarded with the cleared leaves. Left visible they would be vulnerable to predation,
but are fairly quickly able to insinuate themselves into the tiniest cracks in the ha-ha wall and base.
The adults are known to be predators of earthworms and although not being fully equatic, will
survive only in very wet ground and need to return to water to breed. Full breeding condition may-
be achieved after only three or four years.
Triturus cristatus (Laurenti) Amphibia: Salamandridae
The famous Great Crested Newt is without doubt the commonest and most widely distributed
amphibian at Hylands Park. By comparison, I have only ever seen one toad and three frogs at
Hylands. In mainland Europe it appears to be a scarce species and the UK population is said to be
amongst the largest. At Hylands it probably occurs in most of the ponds; as adults I have records
from Ephemeral, Home Fann, Lake Field, Swan, Spring, Pigeon and Ice House ponds with records
of their distinctive young from Ephemeral, Spring and Swan Ponds. It occurs occasionally in odd
places; one I found under a w ooden play-house near Flint Cottage, another I found about 3ft up in
a decaying willow trunk by the Lake Field Pond. Strangely I have never seen it in either of the
formal garden ponds, possibly because of the numbers of potential predators - ducks, moorhens
and very large carp. The Great Crested Newt is protected by UK and European legislation.
Sesia apiformis (Clerck) Lepidoptera: Sesiidae
Although not a rare moth, this species is notable because it is rarely seen and is a spectacular wasp
mimic. The larvae feed in poplar wood for one or two years, before emerging as adults in late June
and July. Grey Poplar seems to be a favourite host locally but other poplars are utilised. It seems to
be at this moment in time a common species around Chelmsford. At Hylands, exit holes have been
observed in hybrid poplar trees in the plantation nearly opposite the Lion Lawn. There have been
reports of Illis species in the horticultural and national press being accorded pest status. It was
implicated in the apparent death or dieback of poplars in Cambridgeshire, Bedfordshire and
Essex Parks: Section 2 - Hylands Park
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