Friday, 17 August 2018

Gilfach (west), Top Llangynwyd

A cold, cloudy, windy day meant when I arrived I had little choice but to shelter from the wind by walking the forestry tracks. I was not expecting much and that's exactly what I got. Only 14 species of hoverfly recorded with nothing special, but it was nice to see Meliscaeva cinctella (26) and Meliscaeva auricollis (9) in fair numbers as they have been absent during the heatwave we just had.

Every cloud has a silver lining as they say. While looking at Angelica for hoverflies I noticed a small well marked moth on the next plant and it turned out to be Phaulernis fulviguttella, a Nationally Scarce B moth with only one previous record in Glamorgan, that being 2002 @ Afon Argoed (MJW) about 7kms away from where I was but the same mountain ridge. Only other insects of note were good numbers of 10-spot Ladybird and a Golden-ringed Dragonfly patrolling.

 Phaulernis fulviguttella - above and below [new for valley, 2nd record for Glamorgan]

 10-spot Ladybird
 Eristalis pertinax
Eupeodes female - potted this one and it turned out to be the commonest species "corollae"

Monday, 13 August 2018

Blaencaerau COP

After two days rain an excellent count of 37 species of hoverfly for August, plus a few specimens to determine later will add to the total. The late summer blooms of Hemp Agrimony, Devilsbit Scabious, Goldenrod, Fennel, Corn and Water Mint backed up by Angelica meant there was plenty of nectar about for hoverflies to feed particularly Water Mint that was covered in flies of all families. A good selection of highlights included Platycheirus peltatus, Chrysotoxum bicinctum, Epistrophe grossulariae, Eupeodes latifasciatus, Leucozona glaucia (scarce this year), Megasyrphus erraticus (2nd valley record), all 7 Eristalis including Eristalis intricarius and Eristalis rupium, all three Helophilus, Sericomyia silentis and a very late Volucella bombylans (plumata form).

Other flies included the Tachinids -  Tachina grossa and fera, Eriorthrix rufomaculata and Thelaria nigripes. 9 species of butterfly were headed by 2nd generation Small Heath and Small Copper. Moths included 3 Silver Y, Ancylis badiana and Udea lutealis. The usual bees, wasps and beetles plus a female Common Darter Dragonfly. I also came across mutated acorns on Pendunculate Oak. These were made by the Knopper Gall Wasp (Andricus quercuscalicis) and is new for the valley.

 Eristalis intricarius (female)
 Helophilus trivittatus
 Leucozona glaucia
 Volucella bombylans - plumata form, a very late individual
 Eriothrix rufomaculata
 Meadow Grasshopper
 Small Heath - 2nd generation
Mutated acorns of Pendunculate Oak, which is caused by a chemical reaction from the larva of the Knopper Gall Wasp. The wasp was introduced accidentally with imports in the late 1960's, since then it has spread throughout England and Wales and reached Ayrshire in Scotland by 2007. It causes serious damage to younger Oaks interfering with the reproductive cycle. A" Defra Plan" is being arranged to eradicate the wasp.

Sunday, 12 August 2018

Tachind flies

As we have had 7" of rain in the last 2 days [not pleasant while driving back and forth to Gatwick (400miles)], there is no way to go out and look for hoverflies. When I'm out looking I always come across other families such as butterflies, bees, beetles etc. But one of the other fly families I usually see are Tachinidae flies known simply as Tachinids. There are 172 species on the family list I have found out, but many need to be caught and examined under magnification to determine the species. Conversely they also have some of the largest and most recognisable flies out there including Britain's biggest fly. I've managed to photograph ten of these species but know very little about their biology. So I decided to do a bit of reading on this family. What I learnt was pretty interesting. Tachinids are parasitiod flies rather than parasite flies, which means they lay their eggs in the host larva species and eat them alive, while parasite flies usually leave the host live. Most Tachinid species are specialist feeders on specific hosts within the butterfly, moths, beetle and bugs families. Identifying Tachinids is not easy as there are very closely related families in the fly group. Generally Tachinids have bristles on the body and have large squamae (fleshy flaps underneath the base of the wings), but the only true way to tell them from other close related families is that they have an enlarged sub-scutellum. This appears as a large fleshy bulge underneath the end of the scutellum when viewed from the side. Below are the ten Tachinids I have photographed with brief explanations on numbers seen, flight periods and hosts.

***** Paul Parsons and Paul Tabor have photographed other species of Tachinids that I have yet to see or photograph.  *****


 Dexiosoma caninum - 26 Jun - 2 Oct (11 records). Host - Common Cockchafer Bug.

 Eriothrix rufomaculata - 21 Jul (1 record). Host - crambid grass moths especially Chrysoteuchia culmella.

 Gonia picea - 27 Mar (1 record). Host - Noctuid moths especially Antler Moth and Square Spot Rustic.

 Lophosia fasciata - 22 Aug - 30 Aug (5 records). Host - Shieldbugs especially Hawthorn Shieldbug.

 Nowickia ferox - 04 Aug - 07 Sep (4 records). Host - Dark Arches Moth.

 Phasia hemiptera - 26 Jun - 26 Aug (17 records). Host - Forest Bug in spring and Green Shieldbug in autumn.

 Tachina fera - 06 Jun - 22 Sep (14 records). Host - Noctuid moths especially Broom, Dun-bar and Pine Beauty. This species is slightly different to other parasitiods because the adult lays its eggs on the foodplant of these moths and the larva wait for the unsuspecting moth larva to feed and then they eat their way in and when finished pupate.

 Tachina grossa - 17 Jul - 09 Aug (13 records) Britain's largest fly. Host - hairy caterpillars especially Oak Eggar and Fox Moth.

 Tachina ursina - 15 Mar (2 records). Host - unknown ?

Thelairia nigripes - 22 May - 24 Jul (40 records). Host - Garden Tiger Moth.


Saturday, 4 August 2018

Garnwen

Recorded a healthy 33 species of hoverfly even though it was 26c, highlights being Chrysotoxum arcuatum (3), 4 Eupeodes species including latifasciatus (3) and lapponicus (1), Melangyna compositarum/labiatarum agg (1)., Sphaerophoria philanthus (1 male) and Eristalis rupium (1).

Other insects included 10 species of Butterfly headed by Painted Lady and my first 2nd generation Dingy Skipper, all my other records are between 16 May and 22nd June. Other goodies included a Hummingbird Hawk-moth, Golden-ringed Dragonfly, longhorn beetle Stictoleptura rubra (male), Tachinid flies Norwickia ferox and Tachina grossa. Birds were notable by their absence.

 Dingy Skipper - first 2nd generation record for me if not the valley.
 Eristalis rupium - with its yellow first meta-tarsus
 Eupeodes latifasciatus (male)
 Hummingbird Hawk-moth - poor shot, wouldn't keep still
 Norwickia ferox -interestingly this species lays its eggs in the Dark Arches moth and the larva eats it alive from within. The fly itself is quite rare and the valley seems to be a stronghold for the species.
Stictoleptura rubra (male) - another rare insect [longhorn beetle] with a stronghold in the valley. The larva feed in rotting wood, especially stacks of felled timber that are present in the forestry. They share this habitat with another longhorn beetle Rhagium bifasciatum, but they have different flight periods, with bifasciatum flying much earlier in the year and their flight period is well over when the rubra emerge. Although the larva can share the same log stack.

 

Monday, 30 July 2018

Top Llan - late post

I photographed this wasp up Top Llan a few days ago, I initially thought it might be a common wasp but didn't look quite right so I put it on Irecord. It turns out that my doubts were well founded as it turns out to be a Norwegian Wasp. Paul Tabor has already had a few records down the lower end of the valley but its new for me. [Even later post - I was back up there on the 31 July, so I did a count of wasps feeding on Hogweed knowing now what I'm looking for and came out as thus - 114 Tree Wasp, 28 Norwegian Wasp, 6 Common Wasp.]




Wednesday, 25 July 2018

Top Llan other stuff

The rain has benefitted other insects beside hoverflies. I recorded 13 species of butterfly including Painted Lady. Bees and Wasps were everywhere and I came across a monster queen Buff-tailed Bumblebee, the biggest I have ever seen it was close to 2" in length. Lots of Plant bugs present too lead by Deraeocoris Ruber. Harlequin Ladybirds have started to arrive also. Tachina grossa (UK's largest fly) out in good numbers as was other tachinid flies. I also came across an orange fly I'm not sure of, so I've put it on Ispot for confirmation if possible. Moths were represented again by numerous Pammene aurana, Grapholita compositella, Silver Y and 6-spot Burnet. I also have 12 new flower blooms for the year.

 Buff-tailed Bumblebee - monster queen
 Harlequin Ladybird - tucked in Hogweed seeds
 Small Copper and Ringlet on Ragwort
 awaiting ID on this one. Will update when confirmed [ID'd on Ispot as "Phaonia subventa" (a muscid fly)- new for valley]
6-spot Burnet

low numbers of hoverflies due to heat - like F**k

Ha!. The moment I moan about low numbers of hoverflies due to the heat. I visit Top Llan (Gilfach (west) and the place is dripping with them, 1/2 dozen on each flowering hogweed plant and there are 200+ plants in bloom. I recorded 35 species with 1000+ flies present. The three species I wrote about in the last blog were all present in high numbers. Episyrphus balteatus a passage migrant largely absent until now was streaming in from a southerly direction and moving along the lanes. Conservative estimate 75 flies. Eristalis pertinax numbered 40 and Syritta pipiens numbered 260 but that was to be expected. Other species seen that were either first for the year or have been scarce this summer were Melanostoma mellinum, Melanostoma scalare, Platycheirus albimanus, Eupeodes latifasciatus, Syrphus ribesii (30+), 6 species of Cheilosia, Eristalis rupium (female), Eristalis tenax, Sericomyia silentis, Volucella pellucens, Platycheirus granditarsus and Helophilus trivittatus. Why so many, well the mist and light rain has brought out the surviving damp/water species and the rain has also seen an explosion of aphids for the species that feed on them at the larva stage so adults were frantically laying eggs.

 aphids on Hogweed were numerous to say the least
 Helophilus trivittatus
 Sphaerophoria scripta
 Eristalis tenax
Platycheirus granditarsus

Monday, 23 July 2018

Heat affecting hoverfly numbers

As I write this, the valley is full of mist and light rain, so seems a bit unusual to make heatwave conclusions right now. But 2018 has been a poor year for hoverflies so far this season and that is due to the unusual heatwave affecting the country. 2017 was typical of the years we have been having lately with wet mild winters and equally wet summers with short intervals of dry warm weather. These conditions worked favourably for hoverflies, allowing the different types of larva feeding to maximize their numbers. 2018 however has reverted back to the weather we used to experience "when we were young", that is extremely cold winters with quite a bit of snow cover. In fact January to May all came in much colder than the average temperatures. June and July on the other hand have been very hot and dry, with drought fears being reported by the national press. Temperatures regularly over 25c have been disastrous for hoverfly larva. The aphid feeders are finding it hard to find food as aphids are the first things to disappear during a drought, The rot-hole larva are just plain dying as all water sources are drying out. This year I have witnessed Myathropa Florea feeding on sap runs and Eristalis nemorum, Xylota segnis and Syrphus torvus all obtaining fluid from exposed mud that is drying out where there should be ponds and streams. Not all hoverflies are affected with Syritta pipiens numbers going through the roof. Below are three graphs of common species, with different larva feeding preferences and how the numbers have been affected so far this year.

Episyrphus balteatus (aphid feeding larva) - is a common European migrant, numbers start arriving in April but pick up greatly in June to August, where the adult lay eggs near large congregations of plant Aphids, then some make it back south, while others try to overwinter. The cold weather from January to May killed off the entire spring brood from the previous summer, so none were recorded until early June. The adults now arriving find that their aphid food source is greatly diminished, so there is no continuation of the life cycle and adult numbers are not inflated by last years brood with numbers crashing. As a migrant this species needs the hot weather to break and the winter to revert back to wet and mild for numbers to recover quickly.

Eristalis pertinax (aquatic type larva) - the larva of this species occur in a wide variety of wet areas, including, streams, silage, manure, wet bogs, damp decaying vegetable matter. The spring brood [from last autumn] hasn't been affected much because the wet habitat had not been overly affected by the cold weather. In fact numbers are higher than normal and looked to have done well in the early part of the year. But as soon as the heatwave kicked in in June numbers plummeted as the larva are dying off in large numbers in the wet places that have dried out quickly because of the drought. In July it should be one of the most numerous of species about, from the graph you can see numbers have plummeted 60%, which is also the number drop for the overall count of the 130 species so far recorded in the valley. Again the weather has to break to see an improvement, as it is multi-brooded this species should be able to recover faster than some other species.

Syritta pipens (aquatic type larva) - this species has seen a dramatic increase in numbers since the drought started and there has to be a reason why. The larva are found in wet decaying organic matter like compost heaps, manure heaps, cow-dung and silage but not in pools or ponds. The reason maybe that as the pools and ponds dry up the silage, compost and manure heaps retain their moisture through the fermentation process within these heaps and are not affected as such by the hot dry weather except to crust on the outside of the heaps, thus the numbers have been less affected. When the larva become adults and fly to feed and breed, their predator numbers are way down and has allowed their numbers to flourish [nature out of balance]. A word of note though, this week I have seen local farmers gathering up their compost and manure heaps and spreading them over their fields to increase grass growth for their cattle and there are few heaps now left. So this species may not be out of the woods yet and a knock-on effect may occur next year unless the weather cools.


Saturday, 21 July 2018

Blaencaerau coal reclamation site

20 species of hoverfly were seen today, but it was definitely an Eristalis day, with all seven of the valleys species being seen. The five common species were in good numbers - arbustorum (20), horticola (12), nemorum (35), pertinax (80) and tenax (8). The two rarer species were also seen and posed well for photographs - intricarius (male), rupium (3). Also seen today was first for the year in Helophilus trivittatus.

The only dragonfly seen today was a male Keeled Skimmer. Tree Bumblebees were the best of 6 species of bees seen. Other insects were the norm except for Tachinid flies, where I recorded Tachina grossa, Tachina fera and Eriothrix rufomaculata. 9 species of butterflies were headed by 13 Ringlet, there was also 4 Silver Y migrant moths.

Both pairs of breeding Stonechat have 3 well grown juveniles. The Swifts have taken flight today with 22 juveniles which equates to 8 pairs, the lower end of the normal counts [8-15 pairs]. The adults kept away from the screaming juvenile pack, they'll all be gone for another year in a day or two, but I think there are at least other 3 pairs acting as if their juvs have not fledged yet. [25th July update - another 10 Juvs have fledged, meaning 32 juvs from 12 pairs which is a slightly better than average year].Three House Martin nests have been located and active [+1 from last year], but no flying juvs yet.

 Eristalis intricarius (male)
 Eristalis rupium
 Tachina grossa
Eriothrix rufimaculata

Thursday, 19 July 2018

Garnwen

30 species of hoverfly were recorded at Garnwen today with the highlight being 3 Eupeodes lapponicus. This is the 3rd year on the trot that I have recorded this species in the valley here, they are the only records for Wales and looks like this species has a stable colony here. Common Fleabane seems to be the favoured food plant for adult flies. Other highlights included Sphaerophoria philanthus and Eristalis rupium.

An impressive 13 species of butterfly were recorded including Painted Lady, Red Admiral, Brimstone and high numbers of Gatekeeper. Bees had all the usual species with Patchwork and Willoughby's Leaf-cutter bees present. The first Stictoleptura rubra longhorn beetle female of the year was present amongst the males. Tree Wasps are now very numerous as was the Tachinid flies Tachina grossa and Sicus ferrugineous..

 Painted Lady
 Peacock
 Brimstone
 Stictoleptura rubra - female with red thorax
 Stictoleptura rubra - male, much paler with black thorax
Dasysyrphus albostriatus

 Eristalis nemorum - with the male above the female in characteristic hovering flight seen only in this species.
Cheilosia impressa - small black species with yellow base to the wings.