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"A Nature Observer′s Scrapbook"

Sawflies



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Figwort Sawfly
Tenthredo scrophulariae Figwort Sawfly larva
Tenthredo scrophulariae

Figwort Sawfly

Tenthredo scrophulariae

At first sight this is very wasp like and at 15mm long, is a similar size to the 'common wasps'. But, it is leisurely in flight and drags its long orange hind legs behind it quite prominently. At rest, it is also quite calm and allows time for close inspection. The absence of a narrow wasp waist then becomes evident, the abdomen does not come to a point and the rectangular head is definitely more fly like.

The front legs are mainly yellow with the exception of the femur which is black behind. The second and third pairs of legs are orange with black femurs.

The wings are tinted orange on the leading edge and fade back to a smoky grey and appear to always be held outstretched at rest.

I found the larval caterpillars a year before positively identifying the adult. I noticed leaf damage on a Water Figwort plant and found a dozen of these large (30mm) white larvae - the likes of which I had never seen before.

At first, I thought they must be moth caterpillars until I had it suggested that they might be sawflies and I began to pick up the clues. They fed with a 'head down' manner and had a broadshouldered look reminiscent of other sawfly grazers. I then found that there was a species called the 'Figwort Sawfly' and that led to verification of the identification.



DateSighting
10.08.2004Mature larvae on Water Figwort growing in ditch opposite front door.
25.07.2005One small larva on Water Figwort growing in ditch opposite front door.
30.07.2005Adult spent a leisurely 20 minutes flying around the Water Figwort.
09.07.2006One adult seen on Water Figwort by mid meadow gate.


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 'Green Legged Sawfly'
Tenthredo mesomelas

'Green Legged Sawfly'

Tenthredo mesomelas

Adult Tenthredo mesomelas are commonly found in England and Wales (but less so in Scotland and Ireland) during the months May to July.

Other than the fact that the larva is active nocturnally, grazing on the leaves of Burdock, Persicaria and Creeping Buttercup, I can't find much information about this sawfly - and my 'common' naming of it is a bit misleading. When viewed from above (as I initially saw it) it does appear be a generally black insect with green legs. But as this image and the other images (linked below) demonstrate, all the under portions of the insect are a bright apple green.

DateSighting
22.06.2003On nettles in meadow western hedge.
08.06.2006On iris leaf by pond.


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Green Sawfly Green Sawfly

Green Sawfly

Rhogogaster viridis

This Sawfly, slightly larger than a Common House Fly, is common and widely distributed throughout Europe.

The adult is carnivorous, feeding on the larvae of other insects, while its larvae is vegetarian, feeding on the leaves of a wide range of plants including, salix (on which these images were taken), alder, poplar, buttercups, etc.

Another image is to be found at www.gwydir.demon.co.uk.



DateSighting
23.05.2004On Kilmarnock Willow in back garden.


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Nematus capreae larva Nematus capreae larvae Sawfly damage

Sawfly - No common name

Nematus capreae (N. miliaris)


Each year these sawfly larvae mount a communal attack on our Kilmarnock willow (Salix caprea pendula). The tree has dense overlapping foliage providing excellent cover for the egg laying site and the first sign of their presence is a mass of tiny larvae stripping the leaves from a concentrated area of the tree.


Whether by accident or design, they would appear to favour the northern, shady side of the tree. All the stripped areas are found on that side. The southern aspect which is fully exposed to the sun, never seems to be targeted.


When disturbed, the larvae which grow to about 20mm in length, adopt the 'S' shaped pose which is characteristic of many sawfly larvae, but they only hesitate form eating momentarily as they satisfy their voracious appetites.


Other images are to be seen at
www.gardensafari.net



DateSighting
10.09.2003Larvae stripped Saix caprea.
06.07.2005Larvae found an the S, caprea again, but much earlier. Maybe there will be two generations, this year.



Sawfly, Dolerus sp.

no common name

Dolerus sp.

The problems of identifying black flies can be daunting. In this case the rectangular shaped head gave the clue that it was a Sawfly.
But, there are several black sawflies, in several genera, e.g. Dolerus, Arge and Rhadinoceraea.
The Arge spp. have short stubby antennae, so that was ruled out.
Rhadinoceraea micans favours Iris plants, and this was found on lush grass - which the Dolerus spp. favour in spring and summer.

That might seem to confirm the Dolerus genus, but there are several similar black Dolerus species which require microscopic examination to ensure a positive identification.



DateSighting
28.05.2007 On long lush grass by drainage ditch.



Sawfly, Dolerus sp.

Sawfly sp.

Dolerus gonager ?
........ or Dolerus puncticollis ?


There are many all black species within the Dolerus genera of sawflies, making them virtually impossible to identify with the naked eye. There are, however, only two with amber/red leg segments - D. gonager and D. puncticollis. But, again, they are difficult to separate without very close inspection.


The Dolerus sawflies do have a distinctive wing venation - although this is often of little help since they tend to fold their wings tightly when at rest! So, it was fortuitous that I managed to photograph this one with wings partially open and showing off its bi-coloured legs.


As its formidable mandibles indicate, it will readily make short work of any softbodied prey that it comes upon. Their larvae are known to feed on grasses.


Of the two possibilities, Dolerus gonager tends to be the most commonly found here in Lincolnshire.



DateSighting
30.04.2012 Found wandering erratically on low foliage


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Turnip Sawfly

Turnip Sawfly

Athalia rosae

As flies go, this one is fairly distinctive. It has a conspicuous orange coloured body with contrasting black shoulder pads.

The adults are found on a wide range of flower heads seeking pollen and nectar.

The larvae feed on the leaves of the Cruciferae family of plants. On hatching, they tunnel within the leaves but then emerge and feed on the underside of the leaves - so they are not seen all that often. On maturity they pupate in the soil.


DateSighting
27.06.2004Pictured on garden Juniper but seen on many other plants.


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Sawfly Arge ochropus

Rose Sawfly sp

Arge ochropus ?

There are several Arge species which look very similar in the larval state so this image has to be regarded as 'representative' of A. ochropus.

It is widely regarded as a garden pest. The larvae are voracious feeders and can strip garden roses of their leaves.

They characteristically feed with their bodies held in an 'S' shape. When mature the larvae pupate in the soil.

The adult sawflies have a black thorax and a yellow abdomen and the two generations a year lay 16 to 18 eggs at a time on the upper, succulent rose stems.


DateSighting
19.08.2004Found de-foliating the front garden roses.
25.08.2005And they, but not as many, are back again this year.


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Rose Sawfly sp

Rose Sawfly sp

..... is it Endelomyia aethiops?

This sawfly larva is smaller and less conspicuous than the previous one and seems not to have the same appetite. It contents itself with grazing the top surface of rose leaves. This creates a mosaic of damage without de-foliating the plant.

It was originally suggested that it might be Blennocampa pusilla but it would seem that that is a 'leaf-rolling' sawfly, and there was no evidence of that on the plant.

I am now more inclined to think that it might be the 'Rose-slug' sawfly, Endelomyia aethiops which is known to be a top surface leaf grazer - but confirmation would be welcome.

Another image is to be seen on the www.hcs.ohio-state.edu page.


DateSighting
29.06.2004Found on front garden roses..


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Pear-Slug sawfly larva Pear-Slug sawfly larva

Pear-slug sawfly

Caliroa cerasi

This larva really does live up to its name. When I first saw it, I really did think it was a small slug. But closer inspection revealed six small thoracic legs and just a suggestion of abdominal prolegs.

Normally found on Pear and Cherry, the first three that I found were on a Japanese Quince bush (Chaenomeles) and were content to graze the upper surface of the leaf - as seen top right of the upper image.

I have subsequently found them on Hawthorn and Blackthorn.

Typical sawfly larva characteristics are that they tend to graze with head tucked down and the end of the abdomen raised.

I was fortunate to find one in the act of moulting (lower image). The procedure of casting its skin took some 55 minutes, and emerging bright yellow must make it very vulnerable at this stage. But, it then slowly changed to a dark grey-green - much better camouflage. And that was the last I saw of it.

I am advised that it is normal for almost all British sawfly species larvae to undergo such a 'prepupa' or 'eonymph' change prior to seeking out an overwintering site in which to pupate.



DateSighting
24.08.2003Larva on Quince bush by pondside in back garden.
21.09.2005Several larvae found on Hawthorn and Blackthorn hedging.
27.09.2008Larvae found on Hawthorn hedging.




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