Showing posts with label entomological key. Show all posts
Showing posts with label entomological key. Show all posts

Thursday, 28 November 2019

Two wings are better than four

Two weeks ago I attended the Introduction to Flies course with the British Entomological and Natural History Society (BENHS), at their headquarters at Dinton Pastures Country Park. The centre is a very friendly and encouraging place, with volunteer tutors helping entomologists to improve their microscopy skills, receive guidance and gain confidence in different invertebrate groups.


The specimens room: rows of microscopes on work stations and cabinets line the walls

'Why study flies?' is a question we are asked A LOT when out in the field (members of public initially assume we are catching butterflies). As well as being important pollinators, they perform a wide variety of ecosystem functions. They make up a big part of the foodchain for other wildlife, they help to break down rotting organic matter and contribute to nutrient cycles. Without flies, quite frankly us vertebrates would not be here.

We don't often need to catch butterflies and the other larger 'macroinverts' for identification, as many are doable in the field or with a clear photograph. Also, there is only a small handful of butterfly species to become familiar with (there are 33 at Gatwick). Identification of flies however can be subtle, as they can be very small and are a huge group of insects, with over 7,180 species in the UK vs. just 59 butterflies!


What makes a fly a fly? They are defined by their scientific name Diptera, which means two wings. They would have four, but the rear pair of wings have evolved into halteres; two stick-like organs which are essential for balance and control, arguably making flies the best fliers. 


Dipterist extraordinaires Barbara and John Ismay led the workshop, with excellent introductory presentations aimed at just the right level of detail. We then sat at the microscope stations and each attendee was given a box of specimens, each labelled only with a number. It was up to us to run through the key and attempt to get each one down to a family.


Practicing with keys reinforces familiarity with the important invertebrate charactertics, such as position of eyes, shape of antennae, veination of wings, even the bristles on the legs.

The key to families of Diptera was pretty simple and easy to use. I will share a few of the initial steps below....

Step 1. Is your body plan freaky as heck, or do you basically look like a fly?

Step 2. Are your antennae rather simple and segmented, or highly modified?


Profile shot of a fancy modified antenna

Step 3. What on earth is going on with that crack in your face?


And so on and so forth, until the key comes out at a family name.


Barbara and John run several workshops each year for the Dipterist's Forum, a group dedicated to the study and preservation of flies. They also run a busy consultancy together while volunteering their time to write papers and, of course, identify flies. Considering they are also married, I reckon this pair could have a side-line in writing couple counselling guides.


The BENHS workshops and field meetings are free and run by expert volunteers. If you do manage to get along to one of the sessions then I highly recommend that you sign up for membership to this worthy organisation.

Wednesday, 28 August 2019

Working with a live specimen

On Friday I found this potter wasp (one of the small, solitary nesting wasps) running around on the landscape contractor's bright green car. I thought I'd have a crack at identifying it to species using just a hand lens, which turned out to be an arduous way to spend a Saturday...


Step 1:  Put wasp in tube into the fridge to anesthetise


Step 2: Take out the book on solitary wasps



Step 3: Turn to first key in book, take chilled wasp out the fridge, start keying...



It seems that everything pretty well matches the family Eumenidae, which takes me to the next part of the book...

Step 4: Keying from the Eumenidae, following on until we get to couplet 7, which is over to the next page.



Oh no!


Ah jeez.


Step 5: Get stool from kitchen, retrieve tiny wasp from ceiling.


She's back in the tube and she's angry.

Quickly, to the next page....



It looks like she's an Ancistrocerus! We are getting there.

Step 6: Continuing on to try to get her down to species...


Hmm, a groove or step on 2nd ventral plate.... Is this it?

To me it looks like there is a step, but then a bulge. It's very difficult to get a decent picture in the hand and at the correct angle. Even after putting her back in the fridge for a while, she simply warms up again very quickly and dashes about.


Might she be Ancistrocerus nigricornis?

I'm just not sure whether this is simply the normal join between two ventral plates on the abdomen. Looking ahead in the rest of the key, it refers to the underside of the 2nd ventral plate, but my pictures are not clear enough. This is where we get stuck without using a microscope and other preserved specimens for comparison.


For many small invertebrates, photographs can only really take you so far in terms of identification, so I'll be told by entomologists that I should have kept the specimen. But seeing as I have a backlog of other material to microscope...

See ya Ancistrocerus sp., back to caterpillar hunting you go. 

Friday, 17 April 2015

The key thing about hymenoptera

My 5th weekend workshop at the British Entomological and Natural History Society (I know, I should just move right in) and I'm realising the best thing about these meetings (aside from the biscuits) is overhearing and chatting with such a diverse group of people about explorations into invertebrate identification.

BENHS HQ - Dinton Pastures workshop desks with light microscopes

Mike Edwards of BWARS led this course on Hymenoptera aculeata (bees, wasps, ants and sawflies), beginning with a presentation on their fantastic diversity and life strategies in the UK. These insects are broadly classified at having two pairs of clear wings (4 in total), joined by hooks and with an ovipositor at the rear which is modified into a 'stinger'. 

The walls are lined with drawers like this filled with carefully preserved and labelled specimens

Mike is an incredibly enthusiastic entomologist, one of many people trying to encourage a new generation of biological recorders. He asked us to bring along our specimens, so I brought some solitary bees from Gatwick, including one of my 'zom-bees' which came back to life after removing it from the fridge. I've subsequently learned a few tips on how NOT to preserve specimens...

...such as storing things in alcohol and then writing the labels in ink

Alcohol will also mat the hairs of insects which can be an important identification feature. 
Plus its a little undignified. This was an Andrena solitary bee, species is probably clarkella 

Just to make a brief point here: I don't collect invertebrate specimens for fun or for ownership (I'm no Pokémon master). Present day Entomologists collect specimens in order to identify a species, and because certain features can only be practically observed when something is no longer moving. You can read more about the entomology code of conduct here:


Identification keys are quite like the 'Choose Your Own Adventure' books, in that you are presented with options and your choice tells you which page to go to. Mike has recently been updating and simplifying a key to British bees, this is a quick demo of part of it...
   For the pics I've used a smart phone down the lense of a microscope, but better naturalists than me will sketch features by hand as this helps with learning!

How to work out if your bee is male or female...

This female had 12 antennal segments...

...and 6 visible tergites (segments) on its rear end

So we know it is female, onto Key 2...



I can see 3 submarginal cells, slightly out of focus

Over to couplet 15...



Surface of eyes are definitely not hairy, and the marginal cell on the wing was relatively broad...

Over to couplet 16...

Couldn't see the tongue, but the wing vein was straight, plus the inner margin of the eyes are more straight than concave; over to 17...

I'm sure you get the jist! This one eventually keyed out to the genus Nomada, which is a type of Cuckoo Bee. These are common parasites of other solitary bees, laying their own eggs which after hatching then eat the larvae and food stores.

Now really is a good time to be getting into wildlife recording; with social media and online recources, everything is so much more accessible. Also, being able to share experiences with people at workshops or online means the entomological pursuit is no longer such an isolating one!

Many thanks again to Mike and everyone at BENHS who helps to put these workshops together.