Mystery Caterpillars by John Agar

Below FoCM Treasurer, John Agar describes some mysterious caterpillars that he spotted on a Chorlton postbox:

On the 10th of June, driving along Ryebank Road, Chorlton, I was puzzled to see that the normally red postbox appeared to be green. On closer inspection I was surprised to see it was covered in hundreds of green caterpillars. I had no idea of what the species might be, however, since moth species greatly outnumber those of butterflies I assumed they must be moth caterpillars.

The postbox was situated approximately three meters from an ash tree growing in a neighbouring garden and behind a privet hedge, clearly one or both must be the host plant. I checked several books, but given that there are in the region of 2,500 species of moth, and many green caterpillars, I was unable to identify the species.

Fortunately help was at hand in the person of, fellow FoCM member, Ben Smart. Imagine my surprise when Ben informed me that the caterpillars were not that of a moth but of an Ash Sawfly, the shape of the head and the five or six pairs of abdominal prolegs being the key to identification. Ben further informs me that there are seven British species that feed on ash (http://tech.groups.yahoo.com/group/sawfly/) .

On checking the photos he`s sure it is the Ash Sawfly (Tomostethus migritus) a species that can experience population explosions leading it to devastate foliage. Ben`s view is that the larvae had descended from the ash in search of further food plant.

The tree had been severely cut back in recent times and the foliage present, although limited, showed no sign of damage. Is it possible that leaf litter from the tree could have been blown into the box and the larvae were emerging from within?
It seems improbable but perhaps not impossible. Why if the larvae were seeking further food plant would they be concentrated in such large numbers on a bright red postbox? I assume that, in common with other flies, they have compound eyes and see colour differently to us, perhaps that answers the question. If anyone can enlighten me please do so.

Ben visited the site but could only find one larva, which he took to try and rear through to absolutely confirm ID.

I am indebted to Ben for his help and input.

John Agar, July 2010

Note:

The Sawflies: Suborder Symphyta

The insects in this suborder have no obvious `waist `between the thorax and the abdomen .They get their name because most females have a saw-like ovipositor, although in some species it works more like a drill. The eggs are nearly always laid inside plant tissue and the larvae are all vegetarian. There are over 400 British species.

Reference:

Collins Complete British Insects by Michael Chinery

Report (rather late!) on the Birdwatching For Beginners walk on 6th June 2010

12 hardy people attended this event, taking place on a drizzly Sunday around Sale Water Park and Chorlton Meadows. The walk encompassed a variety of habitats around this diverse part of the Mersey Valley.

FoCM member John Agar had arranged for the feeders outside the visitors’ centre at Sale to be topped up with food, and, sure enough, his foresight paid dividends as, waiting for everyone to arrive, we were lucky enough to watch a Greater Spotted Woodpecker repeatedly come to take food. This gave us all a chance to test out our binoculars, many of which loaned to us by the Mersey Valley and Countryside Warden Service. Thanks again to them for their assistance on the day.

We set off towards the dipping pond adjacent to the visitors’ centre, pausing along the platform to take in the terrain over the marsh. As if on cue, soon after our arrival, we were treated to the sight of a Kestrel appearing overhead and taking up its distinctive hunting behaviour by hovering above the marsh, only a few feet above us. Even better, we witnessed it make a successful kill, a few of the mammal knowledgeable among us even able to identify the prey dangling from its talons as a short-tailed field vole, which the Kestrel took to a nearby tree to eat. This was a wonderful piece of luck (for us, not the vole!), and goes to show you never know what you’ll see, even on what at first seemed like a wet day, low on promise.

Our walk continued along the brook towards Sale Water Park, from the banks of which we added to our list a Sedge Warbler, betrayed to us by its messy trilling call. Our patience paid off as we were also able to catch glimpses of this elusive bird as it volleyed in and out of cover.

Around the lake we added many more species, including Lapwings, Little Grebes and a family of Mute Swans by the bird hide at Broad Ees Dole.

Our final stretch took us through Chorlton Ees, some of the eagle-eyed among us picking out from nearby woodland a number of Herons hidden among the branches. This was the Heronry, a place where Herons nest and breed, and one of Chorlton Meadow’s ornithological jewels. The more we looked, the more we saw, including one posing at the top of a Larch, silhouetted against the sky analogous more to a mango grove than a beauty spot 2 miles outside the city centre!


Our final ‘star’ species was the Reed Warbler, singing constantly from cover in the reed beds at the heart of the meadows. Hearing this bird’s repetitive and chirring song, as opposed to the more variable song of the Sedge Warbler, enabled us to put our ears to the test and appreciate that for many bird species it’s the aural realm where they’re best admired. A few of us saw the bird occasionally flit through the reeds, but it largely remained in cover, brilliantly camouflaged against last year’s dead reed stems.

For more information on the birds in and around Manchester, pay a visit to the Manchester Birding website, where, among many gems, you can find up-to-date records for what’s been seen in and around Chorlton Meadows:

http://www.manchesterbirding.com/

A complete list of birds we saw on the day.

Blackbird - Sale Visitor Centre
Black-headed Gull - Broad Ees Dole
Blue Tit - Sale Visitor Centre
Canada Goose - Broad Ees Dole
Carrion Crow - various locations
Chaffinch - Cow Lane
Chiffchaff - Broad Ees Dole/River Mersey
Coot - various locations
Cormorant - flying east to west towards Sale
Goldfinch - Stretford Ees/Turn Moss
Great Spotted Woodpecker - Sale Visitor Centre
Great Tit - Sale Visitor Centre
Greenfinch - Hardy Farm
Herons and Heronry - Broad Ees Dole, Chorlton Ees
House Martin - Stretford Ees/Turn Moss
Kestrel (successful kill) - Sale Visitor Centre
Lapwing - Broad Ees Dole and Stretford Ees
Little Grebe - Broad Ees Dole
Long-tailed Tit - Broad Ees Dole/River Mersey
Magpie - various locations
Mallard - Sale Water Park
Moorhen - Various locations
Reed Bunting - Sale Water Park and Chorlton Ees
Reed Warbler - Chorlton Ees
Robin - Cow Lane
Sedge Warbler - Sale Visitor Centre
Song Thrush (star singer!) - Stretford Ees/Turn Moss
Swallow - Mersey overflow
Swan with 6 signets - Sale Water Park
Swift - Stretford Ees/Turn Moss

Julian Robinson, August 2010

Small Ermine Moths by Ben Smart

Many people have remarked, this summer, on the webs smothering certain local trees. Our local Moth expert, Ben Smart, explains all below:

You may have noticed large grey webs coating the leaves of a variety of trees this year. These will usually be made by caterpillars of different species of Small Ermine Moths, and these seem to have appeared in large numbers this year. The particular species can usually be identified on the basis of the tree on which it is feeding. Each web contains large numbers of caterpillars (approx 20-50) feeding gregariously in May and June. Once fully fed the caterpillars move to a nearby branch, form a fresh web, and enter the chrysalis stage of their life-cycle. Again, they do this gregariously, and if you look inside one of these pupal webs, you may see large numbers of chrysalises all lined up together each in its individual white silken cocoon. The adults tend to emerge in June and don’t move far from the foodplant so you may see the adult moth sat on a leaf or on the trunk of the tree. All have small black spots on a white background and are about 1 cm long. The different species are so similar it is often easier to identify the moth by its foodplant.

There are five species that may be found in Chorlton.

Bird-cherry Ermine Moth (Yponomeuta evonymella) – This is the commonest of the family and feeds gregariously on Bird-cherry. It may defoliate the foodplant so much that webs may be formed on neighbouring plants even if unsuitable, in a desperate bid to get the nourishment required for successful development of the caterpillar. This moth can be differentiated from the others as its black spots are smaller and more numerous than the other related species.

Orchard Ermine (Yponomeuta padella) – Caterpillars form webs on hawthorn and blackthorn. The chrysalis has a greenish body with black wing cases. The moth, which emerges from the chrysalis after about two weeks, has a slightly greyer tinge to the forewing than its close relatives.

Apple Ermine (Yponomeuta malinellus) – Webs of these species can be found on the apple trees at Chorlton Water Park. Each contains lots of dense silk, half-chewed foodplant, lots of droppings, and tens of caterpillars. The adult moths are white with grey tips at the end of the forewings, and a small number of black spots.

Spindle Ermine (Yponomeuta cagnagella) – Quite an unusual moth in Chorlton, due to the relative scarcity of its foodplant, Spindle. As with all of these species, with the exception of Y.rorrella, each chrysalis is protected by a white, silken cocoon. The adult moth has a white forewing with a small number of black spots.

Willow Ermine (Yponomeuta rorrella) – A few webs have been found this year on White Willow close to Jackson’s Bridge on the north side of the Mersey. The caterpillar is typical of the Small Ermine moths in that it is grey with a black head and black spots. The adult has a greyish patch on the forewing and grey tips to the wings. The black dots are smaller in size than for most of this family.

Confusion species – There is a moth called the Thistle Ermine (Myelois circumvoluta) that looks similar to these, but is larger, about 1 ½ cm long, and has larger black spots. The caterpillars of this species do not form webs but feed over the winter in the stems of Spear Thistle.

Ben Smart, July 2010

Report on the Fern Walk with the British Pteridological Society - 29th May, 2010

For some, as yet unexplained, reason the area of the Mersey Valley adjacent to Chorlton has a very rich Pteridophyte (i.e. Fern) flora and some 24 species have been found between Chorlton Water Park in the east and the Stretford border in the west - a distance of approximately 2 miles.

On a wet Saturday in May four members of the Manchester and North Midlands Group of the British Pteridological Society (Yvonne Golding, Roland Ennos, Michael Hayward and Dave Bishop) and three guests (Charlotte Abbas, Katherine Miller and David Rydeheard) set off from Chorlton Water Park with the intention of seeing as many of the local fern species as possible. First we negotiated a narrow, sunken lane at the rear of the Water Park and bordering Chorlton Golf Course. Here we encountered Male Fern (Dryopteris filix-mas) and a luxuriant specimen of Scaly Male Fern (D. affinis). We then moved on to the inelegantly named Barlow Eye Tip – once a landfill site but now a Site of Biological Importance (SBI). Here we found three species of Horsetail: the ubiquitous Field Horsetail (Equisetum arvense) but also Water Horsetail (E. fluviatile) and Great Horsetail (E. telmateia). The latter species is interesting because in Manchester Museum Herbarium there are specimens of it which were collected from a site nearby in the mid-19th century. The present colony is on the very edge of the site and may have survived all of the various upheavals which occurred around it in the recent past.

Moving further westward along the river bank we came to another SBI known as Lower Hardy Farm. Here, deep in a Birch and Willow copse, is a magnificent stand of Royal Fern (Osmunda regalis). Unfortunately, there is a plan to drive a spur of the Metrolink tram system through this SBI and across the river to Manchester Airport. Various exploratory drilling operations were conducted here recently and the Osmunda plants came within a whisker of being destroyed.

We then inspected the walls of the Withington Sewage Works Pumping Station. Here can be found Intermediate Polypody (Polypodium interjectum), Hartstongue Fern (Asplenium scolopendrium), Maidenhair Spleenwort (Asplenium trichomanes ssp. quadrivalens) and Rustyback Fern (Asplenium ceterach). The latter species is a lime-lover and one would not normally expect to encounter it in South Manchester, but there is probably enough lime in the mortar of the sewage works wall to support it (the photograph above is of A.ceterach on the sewage works wall). Unfortunately, the spring of 2010 had been exceptionally dry (in contrast to the day of our walk!) and many of these ferns were somewhat shrivelled.

In a wet area at the back of Brookburn Road Primary School nearby we found our fourth Horsetail –Marsh Horsetail (E. palustre). Then a single specimen of Hard Fern (Blechnum spicant) was seen clinging to the steep bank of Chorlton Brook; Hard Fern is a rare species locally.

By this time, lunch at the Bowling Green beckoned - but not before we had seen Black Spleenwort (Asplenium adiantum-nigrum) and Wall Rue (A. ruta-muraria) in the wall of the old St. Clement’s churchyard. In the pub I was able to show the group a frond of Common Polypody (Polypodium vulgare) which I had gathered the day before from a site somewhat off our line of march.

After lunch we made our way towards the Chorlton Ees SBI. Passing through a strip of woodland we saw a specimen of Soft Shield Fern (Polystichum setiferum) with rather deeply cut fronds. About 20 years ago I was told that this species was believed to be extinct in Greater Manchester – but evidently not, because since that time it has turned up in several other places.

In the midst of a derelict hay meadow on Chorlton Ees we saw a large and impressive colony of Adderstongue Fern (Ophioglossum vulgatum). This species was reported from this area by Richard Buxton in his flora of 1849 and by Leo Grindon in his flora of 1859, and was then thought to have been lost until it was re-found in 1995.
We also spotted Lady Fern (Athyrium filix-femina) in the course of our travels and finally, in a patch of Birch woodland on the edge of the SBI, we saw Broad Buckler Fern (Dryopteris dilatata), Narrow Buckler Fern (D. carthusiana) and more Scaly Male Fern.

Challenges for the future are to look for Equisetum hybrids and Dryopteris hybrids (particularly the hybrid between Broad and Narrow Buckler Ferns). In addition, the name ‘Scaly Male Fern’ actually covers a complex group of species, and it would be nice to know how many of these we have locally.

Dave Bishop, June 2010

Bees in the Mersey Valley

On Sunday 20th June Bee Expert, Brian Robinson will be leading a walk and talk focussing on bees. This is a free event and everyone is welcome.

Meeting Place: Mersey Valley Visitors' Centre, Rifle Road, Sale.

Time: 10:00 am to 12:00 noon

Join us to learn about bees and their important pollination role. Brian will give a short talk on bee identification and about some of the different species we have locally. This will be followed by a short walk around some flower rich parts of the meadows to find some bees.

Rachael Maskill and Dave Bishop (FoCM)

Report on Moth, Butterfly and Caterpillar Walk by Ben Smart

This was a joint meeting of the Lancs Moth Group, Butterfly Conservation and FoCM. It was held on the 23rd May, 2010 at Hardy Farm. Ben's report of the meeting is below:

13 attended the walk in baking hot conditions (27oC) looking at this area of the Mersey Valley, where over 600 moths have been recorded. The walk concentrated on those species feeding on birch and on those feeding on grassland, on grasses, vetches and other low-growing plants. Records were made of leaf-mines, larvae and their feeding signs as well as adult moths and butterflies.

Highlights included a beautiful freshly emerged Ruby Tiger (see photograph above), still drying its wings, good numbers of Mother Shipton and Small Yellow Underwing moths, and many caterpillars of Narrow-bordered Five-spot Burnet on vetch, a couple of which had already formed their cocoons on the surrounding grasses. Nine species of butterfly adults were found including the Small Copper, Common Blue and Holly Blue.
Unfortunately no butterfly caterpillars were seen, although the bright orange eggs of the Orange-tip butterfly, laid on Cuckoo-flower, were located.

Another nice find was the Coleophora albidella larval case on Goat willow (albidella), spotted by the eagle eyes of Dave Bishop, Chair of the Friends of Chorlton Meadows. After checking my records I realised that I had once had the adult of this species to light (see adult at http://ukmoths.org.uk/show.php?bf=532 ), but this was the first time I had seen the case of this species. The case is a dark, pistol-shaped structure coated with hairs from willow catkins and was found attached to the upper surface of a leaf doing a good impression of a bird dropping. Other Coleophora species were found on Creeping Thistle (Coleophora peribenanderi) and hawthorn (probably Coleophora spinella), as well as feeding signs of Coleophora serratella on birch.

Numerous Grapholita lunulana were seen. This moth is a fairly recent arrival to Lancashire but is certainly thriving on this site. Although small, it is a very distinctive species, dark in colour with a crescent shape across the forewings, hence the Latin name lunulana.

Another micro-moth seen in numbers was the Cock’s-foot Moth (Glyphipterix simpliciella). A swarm of these moths were seen flying around a clump of Cock’s foot Grass. Careful examination showed that the dried stems from last year were full of the pupal exuviae, and numerous exit holes from which the adults leave the stem once they have emerged.

A Common Frog and Willow Warblers were also recorded.
All this was followed by much needed refreshments in Jackson’s Boat.
This area has recently been threatened by development with proposals from the private landowner (recently purchased from the University of Manchester) to build a football stadium with turnstiles, fencing, 50ft high floodlights and seven football pitches, including artificial pitches. Fortunately this proposal was soundly rejected by the City Council Planning Committee and the developer withdrew his application - although this is unlikely to be the end of the matter.


The full Lepidoptera species list was:
Eriocrania salopiella – mines on birch
Eriocrania semipurpurella – mine on birch
Narrow-bordered Five-spot Burnet – larvae and cocoons
Aspilapterix tringipennella – adult
Phyllonorycter ulmifoliella – mine on birch
Glyphipterix simpliciella (Cock’s-foot Moth) – adult
Argyresthia retinella - feeding signs on birch
Coleophora serratella – feeding signs on birch
Coleophora spinella (prob) – larval case on hawthorn
Coleophora albidella – larval case on Goat Willow
Coleophora peribenanderi – larval case on Creeping Thistle
Elachista argentella – adult
Anacampsis blattariella – larva on birch
Aphelia paleana – adult and larva on Ribwort Plantain and vetches
Celypha lacunana – larva on Ribwort Plantain
Ancylis badiana – adult
Grapholita compositella – adult
Grapholita lunulana – adult
Grapholita jungiella – adult
Mother of Pearl (Pleuroptya ruralis) – larva on nettle
Green-veined White – adult
Large White – adult
Orange-tip - egg on Cuckoo Flower, and adult
Common Blue – adult
Holly Blue – adult
Small Copper – adult
Small Tortoiseshell – adult
Peacock – adult
Speckled Wood - adult
Winter Moth – larva on birch
Latticed Heath – adult
Mottled Umber – larva on oak
Ruby Tiger – adult
Sallow – larva
Dun-bar – larva on birch
Small Yellow Underwing – adult
Mother Shipton – adult

Lancs moth group is at: http://www.lancashiremoths.co.uk/
Information on proposed development of Hardy Farm can be found at http://savechorltonmeadows.wordpress.com/
Photos of all moths mentioned can be seen at: ukmoths: http://ukmoths.org.uk/

Ben Smart, May 2010

A reminder for this coming Sunday’s Birdwatching For Beginners walk

On Sunday 6th of June 2010, Friends of Chorlton Meadows members will be leading a Birdwatching For Beginners walk. It is a free two-hour walk around Chorlton Meadows and Sale Water Park, with the intention of getting beginners young and old into birdwatching.

FoCM members will be on hand to point out any summer visitors and other birds that make their home in this beautiful mixture of grassland, woodland and water habits.

Timetable For The Day

9.45 – 10.00 Meet at Mersey Valley Visitors' Centre, Rifle Road, Sale (near Sale Water Park).
10.00 Introduction, housekeeping and walk plans
10.05 Walk along Sale Water Park to bird hide at Broad Ees Dole nature reserve.
10.35 From Broad Ees Dole along River Mersey to Chorlton Ees.
11.15 Walk around Chorlton Ees and Chorlton Meadows to Jackson’s Boat.
12:00 Arrive back at Visitors’ Centre for final review and dispersal.

Bring binoculars if you can, though some provided by the Mersey Valley Countryside Warden Service will be available on the day.