Journal archives for June 2023

28 June, 2023

Journal Index - UK Hoverflies (Syrphidae) Project

Posted on 28 June, 2023 13:52 by matthewvosper matthewvosper | 0 comments | Leave a comment

Optimise your own observations for the UK Hoverfly Recording Scheme

Did you know that the UK Hoverfly Recording Scheme (HRS - Part of the National Biodiversity Network – NBN, via the Dipterist’s Forum) automatically receives Research Grade observations from iNaturalist? These may then be verified by the HRS. This is a very large amount of data, and improving the overall quality and formatting of that data will make a big difference to the person receiving it! The following information should help you to create observations that are received by the HRS with as much value as possible. (Similar advice will apply to other UK recording schemes).

We can break this down into two parts:
 1) Creating the most useful records on iNat
 2) Getting the most useful observations in the wild!

1) Creating the most useful records on iNat
A good record needs at least three things: an accurate time/date, an accurate location and adequate evidence. These are the same things needed for a ‘Research Grade’ record! But…

   Are your observations licensed for use?

   Are your photos separately licensed for use?

You have separate licence settings for the data and the photographs in your observations. In order for your observation data and your photos to be received by the HRS the licences must be CC0, CC-BY or CC-BY-NC. There is more information about this here and also on the NBN atlas. You can access your licence settings by substituting your username into uk.inaturalist.org/people/YOUR-USERNAME/edit#content (or www.inat... etc if you only use the international site).

   Do you use obscured/private coordinates?

At the moment if you use these privacy settings, recording schemes cannot receive the true coordinates. (‘Obscured’ records will be sent with a 25km radius uncertainty that includes, but is not centred on, the true location). Unfortunately this makes those records completely unusable for the HRS.

At the moment the best alternative is to create a ‘pinned location’ for each of the locations you normally obscure. This location should be a pin in the map somewhere away from the true location, with an uncertainty circle that includes the location. Exactly how large you make the circle’s radius is up to you - 200m, 300m, 1km... but smaller is obviously more useful. This pinned location can be saved so that you don’t have to create it anew whenever you add an observation in that place. It is also possible to retrospectively change your existing obscured records in bulk - but you have to draw the location afresh (you cannot look up your pinned location). More information about how to do these things can be found here. Be aware that the name you give to a pinned location is visible to other users, so don’t call it “My house, 1 Naturalist Way”.

If you do however feel the need to use obscured/private location settings, but you still want your observation to be useful to the HRS, consider submitting it with the true location on the HRS Facebook group – but remember to mention that the observation is on iNat too (give the URL) to avoid duplication.

   …and what is your name?

It is good practice for biological records to be attached to the name of the observer, and it creates a lot of work for recorders if the name is generic or inconsistent. The HRS receives the ‘display name’ from your profile (not your username). Ideally, if you are happy, this 'display name' should be your true ‘full’ (i.e. first + last) name, not a pseudonym, nickname or just ‘Jim’ or ‘Ann’. If you also submit records on other platforms such as iRecord it is particularly helpful if you can use the same name so that all your records can be matched.

2) Getting the most useful observations in the wild!

Ultimately, you will create the most useful data set if you look for hoverflies deliberately, and if you learn about them. Then you will also know what to photograph. You may like to become familiar with a particular site, or a short route that you can walk regularly. You will get to know the best places to find hoverflies and become more familiar with their habits. You will see the way species ebb and flow across the seasons. Over time you will become able to find a greater diversity of hoverflies in the same area.

Check out the post ‘Is it a hoverfly?'

Resources for learning about hoverflies can be found here

Hoverflies prefer to fly in warm sunny weather, but not so much when it is extremely hot. Only a couple of species fly in the winter. Mid-morning is often regarded as the best time of day. They are keen pollinators, so check flowers - plants with collections of shallow flowers, such as umbellifers, hemp agrimony, dandelions, thistles and burnets are particularly popular as well as willows and Prunus species (especially blackthorn) in the spring.

Not all hoverflies are best found this way - some like to bask on sun-drenched foliage, others are attracted to sugary sap runs. One way to attract hoverflies on cool or dull days is to spray foliage with a solution of sugar in water. Another strategy is to seek out the places female hoverflies like to lay eggs: Hoverflies in the subfamily Syrphinae feed on aphids in the larval stage - you may find females laying eggs near aphid colonies; Many hoverflies in the subfamily Eristalinae have aquatic larvae - so look for them around ponds, stagnant pools, or rot holes in trees (look away from fast flowing currents though).

Many hoverflies are identifiable from quite poor photos, but a fair number are difficult or even impossible to identify the exact species, even from excellent photos. To give yourself the best chance when photographing hoverflies (and indeed any flies) try to get (in order of importance):

 1) a top-down angle: get the wing venation in focus if you can. This will normally get you the genus and often the species. It is usually best if the wings are open, showing the abdomen.

 2) The next best angle to get is from the side showing the legs - sometimes the colour of the feet or the hairs on the legs are valuable

 3) If you can, get the face from the front (i.e. showing both above and below the antennae).

 4) Obviously the more angles, and the more detail the better. It is worth trying to get a distant photo first - just so that you’ve definitely got something, then go in for the closer, more detailed shots which run a greater risk of frightening it away.

Happy hoverating!

Posted on 28 June, 2023 13:52 by matthewvosper matthewvosper | 3 comments | Leave a comment

Is it a Hoverfly?

Hoverflies are probably most often thought of as those black and yellow mimics of bees and wasps in the subfamily Syrphinae but there’s really a lot of diversity in the family on top of these so a few extra pointers may be of use.

1) Hoverflies are flies!
That means they have two wings, not four like bees and wasps. Also, most hoverflies lack the narrow ‘wasp-waist’ characteristic of most bees and wasps (although there are a few that mimic the waist a bit). The wing venation is also quite simple compared to bees and wasps. The next pictures illustrate this and also some of the other points that will be raised below.

A hoverfly A bee (Megachile)


2) Hoverflies are Brachyceran (‘Short-horned’) flies.
That means that they have short antennae with only three segments, unlike ‘Nematoceran flies’ and bees/ wasps, which have long antennae with many segments. (See above - and don't be confused by the long bristle attached to the antennae) A few hoverflies, like the one below do mimic the long antennae of bees/wasps, but if you look closely they still only have three segments - just three elongated segments!



3) Hoverflies are Aschizan flies.
That means their face doesn’t look like the Sarcophaga below - with white tracks next to the eyes and a big cavern in the middle of the face below the antennae. Most other Aschizan families are rather small creatures.

A hoverfly Not a hoverfly (Sarcophaga)


4) Hoverflies are not bristly.
A few species (notably Volucella sp) have some discreet bristles - but if your fly looks like a punk rocker, it’s not a hover!

Not a hoverfly! (Tachinidae)


5) Hoverflies have big eyes!
They cover most of the sides of the head - and in males they usually meet in the middle of the top part of the head. They are not as comically big as in the family Pupunculidae however! (That’s another Aschizan family - probably the most similar to hoverflies)

6) Wing venation.
Hoverfly wings have:
 a) a ‘vena spuria’ (spurious vein). This is not a true vein - it is not connected at either end (so it is also sometimes called the ‘floating vein’). It is actually a toughened fold in the wing. Only hoverflies have this, and only one British hoverfly does not have it (Psilota anthracina)
 b) a ‘false margin’. Cells ‘dm’ and ‘r4+5’ are well separated from the back edge of the wing by a vein.
 c) a long pointed anal cell that doesn’t quite reach the back edge of the wing.

HOVERFLIES
Eupeodes Eristalis
Eumerus Microdon
NOT HOVERFLIES!
Pipunculus (Pipunculidae) Eriothrix (Tachinidae)
Posted on 28 June, 2023 13:52 by matthewvosper matthewvosper | 0 comments | Leave a comment

UK Hoverfly Resources




Websites:
The Hoverfly Recording Scheme has a Facebook group here

Steven Falk’s Flickr site contains information and photographs on almost every British species. (It also contains a lot more than just hoverflies)



Books:
Britain’s Hoverflies (WildGuides) by Ball and Morris is the best introductory guide to UK hoverflies. A new edition is due in September (now delayed), but it is already available for preorder.

Hoverflies: An Illustrated Guide by Stubbs and Falk is comprehensive (except for a small number of recent additions to the UK’s list of hoverflies) and more advanced, but still accessible for those with a real interest.

Hoverflies of Northwest Europe: Identification Keys to the Syrphidae by van Veen is a book of identification keys that includes all of the UK species but also the other species of hoverfly in the wider region. It is most powerful with specimen in hand as not all of the features it uses are visible in photographs, but there is also plenty of information that is useful for photo-identifying this wider group of hoverflies.

Hoverflies of Britain and North-west Europe by Dutch specialists Sander Bot and Frank de Muetter looks exciting; obviously it will cover non-UK species too. It is due out on 26th Oct.




Other resources on iNat relevant to the UK fauna:
There is a separate project specifically for UK hoverfly larvae that also feeds in the HRS

The following resources by iNat users are arranged taxonomically with the author’s username in parenthesis:
Subfamily Syrphinae:
Tribe Bacchini
Mapping UK Platycheirus recording groups onto iNat taxonomy (matthewvosper)
Key to British Male Platycheirus Incorporating the Main Infrageneric Groupings in iNat (matthewvosper)
Key to British Female Platycheirus Incorporating the Main Infrageneric Groupings in iNat (matthewvosper)

Tribe Melanostomini

Tribe Syrphini
Identifying Sphaerophoria in the UK from Photos (matthewvosper in UK Syrphidae Project)
Key to the Syrphus of Europe (matthewvosper)
Identifying Syrphus in the UK from Photos (matthewvosper in UK Syrphidae Project)
Xanthogramma Species in Europe (carnifex)

Subfamily Eristalinae:
  Tribe Brachyopini
  Tribe Callicerini
  Tribe Cerioidini

  Tribe Eristalini
Distinguishing Eristalis arbustorum and Eristalis abusiva (matthewvosper)

  Tribe Merodontini
  Tribe Milesiini
  Tribe Rhingiini

  Tribe Volucellini
Volucella of the West (Europe, Africa and the New World) (matthewvosper)

Subfamily Microdontinae:



If you know of other resources that should be linked to here, please mention them in the comments.

Posted on 28 June, 2023 13:53 by matthewvosper matthewvosper | 0 comments | Leave a comment

Determining and Annotating the Sex of Hoverflies in iNat


You may find it productive to add the sex annotation to hoverflies - it can be a lot quicker than identifying, and it's a good way for a starter to see the range of hoverfly diversity. It is useful to record the sex of a hoverfly, as they can have different behavioural patterns, they don’t necessarily occur in a 1:1 ratio, and they may also have different phenology. They can also look different, and it’s useful for interested learners, iNat identifiers, or indeed researchers, to be able to call up all the male observations, or all the females. When I (MV) identify Syrphus or Platycheirus for example, I usually identify the males and females separately, because there are different features to look for.
There are two things to address here:
 1) How do you tell the sex of a hoverfly?
 2) What is the best way to add the sex annotation?

Thankfully, determining the sex of a hoverfly is usually easy. Adding the sex of a hoverfly to other people's observations in iNat is also easy, and quick to do in large numbers. (To add the sex to your own observations as you upload see here). Let’s take the second thing first.

Most efficient way of adding annotations
The quickest way to add annotations in iNat is using the ‘Identify’ portal. Once you have filtered for ‘Hoverflies’, ‘United Kingdom’, (and for your own observations if you are only doing your own after upload), click on the first observation you want to add the sex to and navigate to the ‘Annotations’ tab.

This link will get you all the UK Hoverflies without a sex annotation: https://www.inaturalist.org/observations/identify?quality_grade=needs_id%2Cresearch&taxon_id=49995&place_id=6857&without_term_id=9
If you want to see just your own observations add ‘&user_id=YOUR USERNAME’ to the end of the URL.

Annotations can be added by clicking, but it is quicker to use keyboard shortcuts: for sex use the combination ‘s’ (for sex) followed by ‘m’ (for male), ‘f’ (for female) or ‘c’ (for cannot be determined). Please do not use ‘cannot be determined’ just because you cannot determine it - it means that determination is impossible. Note that annotations do not work like IDs in iNat - if you get it wrong other people cannot out-vote you.

(It is also very helpful to add the annotation for ‘life stage = larva’ which enables the Hoverfly larvae project to collect the observation. Use ‘l’ (for life stage) and ‘l’ again for ‘larva’. Similarly 'l'+'a' for adult and 'l'+'p' for pupa.)

Use the arrow keys to move onto the next observation.

Using this method it is possible to add annotations to a large number of observations very quickly.

Unfortunately there is no way to annotate for a mating pair using the main annotation function. Leave these without a sex annotation.

You may find it easier still if you filter to a smaller taxon - for example Subfamily Syrphinae or a Genus e.g. Eristalis. That way you are looking at the same sort of fly every time making recognition quicker, and it also reduces the number of exceptions you have to think about.

Determining the sex of a hoverfly
It is possible to tell the sex of a hoverfly from behind if you can tell the difference between a male genital capsule and a retracted female ovipostor - but by far the easiest way to tell is using the eyes. In almost all species, the eyes of a male are connected above the antennae (called ‘holoptic’), whereas the females’ eyes are widely separated (‘dichoptic’).

Females Males

In the Subfamily Syrphinae there are no exceptions to this rule and, regardless of the species, absolutely any hoverfly with connected eyes is definitely male (no exceptions there). There are however some groups where the male eyes are separated. The main exceptions are those genera in the Subtribe Helophilina with stripes on top of the thorax (i.e. the genera Helophilus, Parhelophilus, Anasimyia, Eurimyia and Lejops). In these genera the male eyes are closer together, but not by much. In the males however the edges of the eyes are parallel at the top of the head, whereas in the females they diverge; there are often also markings on the female frons that are different to males - this should be checked for individual species. The example below is Helophilus pendulus

Female Male


Other groups that are exceptions are the rarely recorded genus Microdon (the only British genus in the Subfamily Microdontinae: Ant-flies), the subtribe Spheginina (Genera Neoascia and Sphegina) which are delicate small flies with a long narrow waist and a bulbous tip to the abdomen, and the genus Lejogaster, shiny dark metallic flies with a concave face and rather bulbous antennae. These are very difficult to tell the sex, best to leave them unsexed to be honest. Familiarise yourself with how they look using the links to Steven Falk's pictures, and you will be able to steer clear of them.

A very important isolated exception is the common Eristalinus sepulchralis: in this case again the male eyes are parallel to convergent at the top of the head and the females' are divergent, but compared to Helophilus etc there is a much greater difference between the sexes - i.e. the females' eyes are significantly more separated than the males'.

Another isolated exception is the very rare Eristalis abusiva, although in that species the eyes come so close that they are unlikely to cause confusion.

MALE Eristalinus sepulchralis MALE Eristalis abusiva (Photo credit @jeanpaulboerekamps)

Steven Falk’s Flickr is an ideal source for checking photographs of the exceptions mentioned above.

A final note: you will occasionally see a hoverfly with its abdomen greatly extended into a long pointed tube shape: this is the 'ovipostor'. Usually the ovipostor is retracted inside the abdomen so you can't see it. It is extended for the purpose of laying eggs - obviously therefore a hoverfly with an ovipostor is a female!

Posted on 28 June, 2023 13:53 by matthewvosper matthewvosper | 11 comments | Leave a comment

30 June, 2023

Key to the Greenbottles (Lucilia) of Europe with some notes on Africa

The genus Lucilia is very difficult to identify from photographs (as are many other genera of blow flies). But the greenbottles are also very commonly observed, and there is a tendency to overidentify certain species (I'm looking at you sericata...). Most people I know are surprised to discover that there are eight species of greenbottle known just from the UK. There are a further three species in the rest of Europe. As a result of this perfect storm, Lucilia observations on iNaturalist are, frankly, a bit of a mess.

The presentation below should give an idea of what it is necessary to photograph in order to have the best chance of getting identifiable pictures. To spell it out:
 1) The bristles on the top of the thorax
 2) The base of the wing from the front (not the top)
 3) The bristles on the middle tibia (the best angle is to look toward the front of the side of the thorax from just a position just back of the middle leg.
 4) The space between the eyes (frons).

The key below is primed for use with photographs but, even so, identification will frequently be impossible. Hopefully it will raise awareness and increase people's confidence to tackle the huge and tangled backlog of observations on iNaturalist.

Which brings me to... Africa! As far as I can tell there is only one additional species of Lucilia in Africa: Lucilia infernalis. This species is immediately distinctive because of the extensive and dark infuscation on the leading half of the wing. I do not know much else about it except that it is widespread in the Afrotropical region, but a picture of it can be seen in Figure 5 of this paper. This is more likely to be confused with certain species of Chrysomya - particularly C laxifrons. Chrysomya can be distinguished by the black margins of the tergites, and the wing infuscation is much better defined in those species that have it. I cannot confidently give a list of which European species may also be present in Africa - I know that L cuprina and L. sericata are widespread on the continent, but others may also be present especially in the north. I believe that only those two species are present in Arabia, so there is little risk of Asian species impinging on East Africa.

The Key below covers the European species and also gives information about how to distinguish 'True greenbottles' from lookalikes. Species found in the UK are underlined. The usual caveat applies: I've made this for my own learning and hopefully for the benefit of others, I believe it to be accurate and based on sound sources carefully considered - but I am not an expert, and Calliphoridae are even outside of my normal activities, so bear that in mind.

The species covered are: Lucilia ampullacea, bufonivora, caesar, cuprina, illustris, magnicornis, pilosiventris, regalis, richardsi, sericata and silvarum.

Posted on 30 June, 2023 20:44 by matthewvosper matthewvosper | 6 comments | Leave a comment

Key to the Greenbottles (Lucilia) of Europe

A link to some content on : matthewvosper's journal

Currently there are coordinated efforts to search for Lucilia observations in Africa and Asia.

So far, only two confirmed blowflyesque species are known in Antarctica: One fossil and lab-reared [Lucilia sericata](https://parasitesandvectors.biomedcentral.com/articles/10.1186/s13071-020-04543-y) for microbiology research. Likely invasive candidate L. sericata remains plausible but not confirmed.

Posted on 30 June, 2023 22:06 by matthewvosper matthewvosper | 5 comments | Leave a comment