Erratum: Demons not Killers

Updated: 30.01.2025

All Dikerogammarus species are non-native invasive species which are potentially harmful to other aquatic life. There are at least two species present in the UK and microscopic examination of the projections on the urosome is required to distinguish between them. In June 2024 I found a specimen of Dikerogammarus in the River Soar in Leicester (described below). At the time I identified this as D. villosus, however, recent correspondence with the Environment Agency has resulted in correction of my I.D. to D. haemobaphes, the "Demon Shrimp".  At one level this makes no difference, but D. haemobaphes was previously known from the Soar so my find is not in fact a new invasive species for VC55. 

Reference: Dobson, M. (2012) Identifying invasive freshwater shrimps and isopods. Freshwater Biological Association. Available at: https://www.nonnativespecies.org/assets/InvasiveFWShrimpsIsopods.pdf

 

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Yesterday I found a single specimen of Dikerogammarus villosus in the River Soar near Leicester. Popularly known as the "Killer Shrimp", this species was first identified in the UK in 2010. It is true that this is a voracious predator, killing invertebrates and small fish. It is also a highly successful colonizer, having swept across Europe from their origin in eastern Europe. This isn't the first time this has happened, other Gammarids have colonized the UK in successive waves, e.g. Gammarus pulex and Crangonyx pseudogracilis. A closely related species, Dikerogammarus haemobaphes, is well established along the Soar, but my recent find is the first VC55 record for D. villosus, which has been demonized even more than its congeners (Killer!). Papers published in the years after its UK arrival predicted dire consequences, including problems with biotic indices for water quality assessment - after the Killer Shrimp has eaten everything else ("Killer shrimps", dangerous experiments and misguided introductions: how freshwater shrimp (Crustacea: Amphipoda) invasions threaten biological water quality monitoring in the British Isles. (2012) Freshwater Reviews, 5(1), 21-35. https://doi.org/10.1608/FRJ-5.1.457). 

D. villosus is certainly tough as old boots - pollution tolerant (which is *very* helpful in British waterways), salt-tolerant and can survive in damp conditions for up to five days so it can potentially be spread by equipment including fishing gear, nets, boats, kayaks and trailers. And yet, fourteen years after its introduction, the distribution of this species still appears to be relatively restricted - it certainly hasn't spread as rapidly as first predicted. Part of the reason for this is certainly under-recording - identifying D. villosus requires close examination - but is relatively straightforward (see: https://www.nonnativespecies.org/assets/Uploads/ID_Dikerogammarus_villosus_Killer_Shrimp_v2.1-1.pdf ). 

Even so, this species has not swept across the country quite as easily as predicted. We need to take sensible biosecurity precautions such as disinfecting nets and equipment - but that doesn't deal with wild birds, etc. Even so, maybe the Killer Shrimp!, like the Killer Harlequin Ladybird! and the Killer Asian Hornet! - may not be quite as bad as first feared. It is another undesired pressure on aquatic ecosystems, but I'm a lot more concerned about pollution than I am about Killer Shrimp! 

  

Air-bags Deployed!

On a recent trip I learned something interesting about Malachite Beetles.  I popped a specimen in my new spi-pot for a quick record shot and when I looked at the photo I noticed four triangular triangular pinkish "things" attached to it.

They didn't look like ectoparasites so I wondered if they could be orchid pollinia, lots of Common Spotted-orchid being present. However, when I asked on Facebook Michael Geiser kindly informed me that these structures are in fact a chemical defence system consisting of inflatable membranous "air-bag" like pockets. These produce a pheromone presumably targeted at ants and other smaller predators, to fend them off. All members of Malachiinae have this kind of chemical defence, inflate their "air bags" when feeling threatened. 

On release, the beetle wandered off unharmed, presumably quite pleased with itself - but who knows what goes on in the mind of a Malachite Beetle?

 

New! Improved! Spi-pot

 

A "spi-pot" is a very useful gizmo for examining or photographing details of insects needed for identification, e.g. if you need to photograph the underside of a specimen which won't conveniently lie on its back. If you Google "spi-pot" the standard instructions for making one involve using clingfilm as a clear window through which the insect is observed. In my experience, this doesn't work very well in the field as the plastic film soon crinkles and marks and has to be replaced after a few uses. I've been using a plastic specimen tube with a foam plunger for a while but these tubes soon accumulate marks which interfere with detailed photos. I haven't been able to find any flat bottomed tubes which are free of moulding marks or writing, and glass would be far better for photography as well as more robust then soft plastic. Today it dawned on me that I could saw the bottom off the tube and tape a 5cm glass petri dish (available online) on the end. A simple hack but coupled with the Olympus TG6 a powerful tool for identification.

 

Ozyptila simplex

It's been a couple of years since I've managed to add any new spiders to the VC55 list, so I was very pleased to find a specimen of Ozyptila simplex yesterday. This one looked interesting from the moment I clapped eyes on it so I was pleased when my initial feeling was confirmed. At first sight, the habitat, a dampish meadow with rank vegetation on the banks of the Welland, seems a bit odd for a species normally thought to be associated with sand-hills, coastal grasslands, and estuarine habitats, but it is known to live in inland grassland habitats including fens and reed-beds in Europe. Yet another example of a species on a North Westwards march. 

A Hatch of Harlequins

For a recent ladybird walk I popped a few specimens in tubes so I could do the "Here's one I found earlier" trick if necessary (thankfully not needed, we found plenty of ladybirds). On returning home, I found a couple of the Harlequin Ladybirds, Harmonia axyridis, I had taken to show the three main colour forms had laid eggs in the pots.  I released the females and decided to document the development process. 

Five days after laying the first change could be seen, a slight darkening of the eggs and the legs visible down one side of the egg. Six and a half days after being laid, the larvae emerged. Emergence was well synchronized, designed to prevent their highly carnivorous siblings eating the unhatched eggs. 

On hatching, the larvae hungrily chowed down on the egg shells for a few hours, but it clearly wasn't going to be long before they started on each other. I'm not sure how to feed first instar larvae, which are a bit small for most aphids. There are various artificial diets published but research papers show these are a poor substitute for natural foods, so the simplest solution would be to let them cannibalise each other and then move the strongest larvae on to aphids for subsequent instars. I have little experience rearing insects and my few attempts have been fairly unsuccessful, so because I was feeling quite protective of my little house guests I distributed them across our aphid-infested Honeysuckle where they will do some good. I like to think they didn't get such a rough deal, protected from a pretty awful week's weather and, more importantly, all those nasty Ichneumons, before being freed to go about their lives.  

  

Entomology Journal - May 2024

A better month for entomology, although the weather put a damper on fieldwork again at the end of the month. 

The Beast from the East

If you believe what you read, the weirdly alien Delphacid planthopper Asiraca clavicornis appears to be declining nationally. Except that it isn't, well not in VC55 anyway. Over the past year we have added three new sites for this species in VC55. Notably, these are possibly the three best recorded sites in the vice-county, so it seems that this bug is newly arrived, and now it's here it's spreading. My guess therefore is that this species is not so much declining as migrating north and west - a familiar theme. 

My Journal, May 2024

04.v.2024

An encouraging spring feel in the garden this morning with Green-veined Whites and a Peacock on the wing. Good numbers of aphids have appeared on many plants so the bloom of Hemiptera can't be far behind.

05.v.2024

Took advantage of a beautiful spring morning to take the sweep net for its first outing of the year. Finally a feeling of entomological abundance - very good range of bugs - and I was able to put the new magnifying visor to the test.

06.v.2024

A disappointing 16/6 in the moth trap although the temperature did eventually drop off to 5C despite the cloud. Social media tells me that all moth trappers are struggling with numbers - I don't know whether to be relieved that it's not just me or alarmed at the loss of insects (it's not just moths, there's a complete lack of by-catch too).

07.v.2024

A day's "sensitive" gardening, trying to deal with the thugs without too much wildlife damage. Watching the Great Tits feeding chicks in the nestbox was a good diversion. At dusk, the widowed Blackbird belted out a lonely song from the TV aerial, and I saw the first bat of the year in the garden.

08.v.2024

Another fine day so I spent an hour tickling the Oak catkins. The summer Mirids are here.

10.v.2024

After what seemed a perfect night (warm, calm, no moon), a disappointing 4/4 in the moth trap. Another morning's garden thug refereeing. The Great Tit chicks are loud now in the nest box. In a difficult season it looks like the parents have got the timing right, plenty of caterpillars going in there.

11.v.2024

A visit to the far east - Bloody Oaks. What a magical place this is, and it didn't disappoint. I recorded a number of personal firsts, such as Turtle Shieldbug, Podops inuncta, plus putting dots on the map for quite a few species I have routinely been recording this year, greatly extending their known distribution way out east. This highlight however has to be Asiraca clavicornis, a new site for this species, see above. Ash Die-back has taken a sad toll on the Rutland verges. I fear the ratchet effect - first the Elms, now the Ash, then the Oaks?

13.v.2024

A very enjoyable afternoon outing with friends. Productive too, between us we managed to generate lots of good records, my favourite being Aradus depressus, beaten from Hawthorn.

15.v.2024

Having accumulated quite a backlog of specimens, a microscope day was in order. This turned out to be fortunate in view of the thundery showers regularly punctuating the day.

16.v.2024

More rain. More microscope.

17.v.2024

A morning gardening followed by an afternoon sorting out the hoppers from Bloody Oaks. A good range of species and thankfully my brain is not as rusty as it often is at the start of the season. Slowly some of this stuff is starting not only to sink in but to stick.

18.v.2024

Slightly more encouraging signs from the moth trap but still only 13/6. The by-catch was better however, the first microcaddis for the year and two species of (unidentifiable) Psallus.

19.v.2024

Another visit to the Far East, the land beyond the A1 - Stretton. Visited two poorly recorded woodland sites and amassed a reasonable list of species.

20.v.2024

Another day out sampling the delights of East Goscote. Specimen backlog has now reached epic proportions.

21.v.2024

A damp day specimen sorting.

23.v.2024

My new talk "A Loveliness of Ladybirds" was well attended and seemed to be well received. Some good questions at the end, only a few anti-insect ones (biting). Why are people obsessed with insects trying to kill them? Fingers crossed for the weather on the follow up walk.

25.v.2024

A late May evening, 3 moths in the trap, and one of those was a migrant Silver Y.  OK, it did eventually get down to 5C and there was a full moon, but the disastrous moth collapse continues. Hogweed flowering outside the kitchen window is attracting an entertaining range of Diptera in the occasional sunny spells. In the afternoon, the Ladybird Walk in the local park was blessed with fine weather and an enthusiastic group of ladybird spotters from a wide age range. Eight species of ladybird spotted.

26.v.2024

Karma - what goes around comes around. A little bit of off-syllabus bug potting while talking about ladybirds yesterday also yielded a Pine Cone Bug, Gastrodes grossipes, plus Plesiodema pinetella, both from Scots Pine. Result!

Read previous Journal entries

 

The Beast from the East

 

If you believe what you read, the weirdly alien Delphacid planthopper Asiraca clavicornis appears to be declining nationally. Except that it isn't, well not in VC55 anyway. Over the past year we have added three new sites for this species in VC55. Notably, these are possibly the three best recorded sites in the vice-county, so it seems that this bug is newly arrived, and now it's here it's spreading. My guess therefore is that this species is not so much declining as migrating north and west - a familiar theme. 

 

Entomology Journal - April 2024

Not as much entomology as I would have liked this month due to the weather (April 2024 - the spring that never was?), other commitments, and a troublesome injury. 

What the well-dressed entomologist is wearing this season

I dropped and broke my ancient over the counter magnifying glasses, and even SuperGlue couldn't rescue them, so this cheap eBay visor is on trial. Definite Blade Runner vibe. 

How Bad Are Bananas?

I will try to stop going on about my current climate obsession every month (although I can't make any promises), but if you're interested, you should read this book. Berners-Lee's approach to this complex area is impeccable and will inevitably be thought provoking, most notably to focus on priorities, e.g. don't worry about how to dry your hands if you ever fly - the difference between towels and electric hand driers is negligible in comparison. So, no, I don't have a 5 tonne lifestyle (although I'd like to), but I'm trapped by the paradox of embedded carbon. 

Berners-Lee, M. (2020) How bad are bananas? The carbon footprint of everything. Profile Books.

My Journal, April 2024

01.iv.2024

A showery start to the month. Worked through the Soar Corixids from Croft. Tricky but I am now much more confident with this group than I was.

02.iv.2024

A visit to an unexpectedly sunny Ulverscroft was a nice morning. The Hawthorns are just at the bud burst stage, and frankly looking a bit sparse still. Nevertheless, beating the emerging foliage was a good source for some interesting insects. First is the charming little Lacebug Physatocheila dumetorum, which was surprisingly abundant . This species favours Hawthorn but I have previously taken it from lichen-covered Larch, although the overwintering Larch specimen was very tatty. The Hawthorn today was alive with these bugs, but the species is seriously under recorded, mostly because of the small size (2-3mm) I suspect. Of course I also came across the Hawthorn Leaf Beetle, Lochmaea crataegi - an attractive bonus species! 

04.iv.2024

A nice spidery afternoon. Quite staggering how rapidly ObsIdentify is progressing with Linyphiids.

05.iv.2024

Fiddled around with a new underwater macrophotography setup using one of my long suffering Large Red Damselfly nymphs as a test subject. Reasonable results but more fiddling is required. For more, see: Coffee anyone? Underwater photography for landlubbers

06.iv.2024

On the train it is noticeable how much the trees have greened up, particularly the willows along the Soar. Longed to be out there splashing through the puddles with a sweep net (Storm Kathleen winds eliminate the possibility of beating).

07.iv.2024

As Storm Kathleen sends gusts of faded Blackthorn petals across the garden, on this date in 1775 Gilbert White writes about the same thing, a " Blackthorn winter".

08.iv.2024

Finally managed to mow the meadow. Still far too wet to be on it but there doesn't seem to be another opportunity so it seemed the least worse option (compared with the more delicate species being choked out by the thugs). Sadly this meant having to sacrifice most of the Cowslip flowers. The Collared Doves nesting in the garden have become very stroppy, taking on all comers, including the Magpies.

11.iv.2024

Finally a beautiful spring day so I took the microscope for a drive in the countryside, returning home properly lubricated and dust free, as was the microscope. Ran the moth trap for the second time this year. Only 8/6 moths but some nice specimens.

12.iv.2024

Inspired by yesterday's discussion I dug out my old manual focus rail and used it on the by-catch from the moth trap. Very happy with the results and can't figure out why I haven't done this before.

14.iv.2034

Swiftly flows the Soar. CEH predicts river flows in the East Midlands will be above average for the next three months - a pretty safe bet. A short visit to Everard's Meadows and the first outing with the vacuum for some time, sampling banks newly emerged from the floods. I couldn't resist beating the Sallows though in the hope of something unusual.

15.iv.2024

A "squall line" produced a remarkable start to the day with thunder, lightning, torrential rain, hail, snow and 50mph winds. Huddled over the microscope working in specimens from yesterday.

16.iv.2024

Took a short interthunderstorm walk to Knighton Park and managed to pick up a few bugs (despite the wind) as subjects to fiddle with photography setups during the afternoon tempest.

18.iv2024

Early morning chaos in the garden as Magpies raid the Blackbird nest for the second year in a row. Chicks were close to fledging and at least one escaped so some may survive.

20.iv.2024

A very enjoyable trip to Bagworth Heath with pleasant company. Blessed with sunshine although recent weather means insects are still in short supply. In the garden the Collared Dove chicks have fledged.

Late April 

A family holiday curtailed nearly all entomology, as I was not allowed to pack any entomological equipment. Only armed with a phone camera I was still able to stick my head in a hedge a couple of times and come up with a few goodies, my favourite being the Firebugs, Pyrrhocoris apterus, massing in early season mating aggregations. I also found an 11 Spot Ladybird, Coccinella undecimpunctata, present in VC55 but not common here. 

Read previous Journal entries

Coffee anyone? Underwater photography for landlubbers

 

A great tip from David Pritchard on the Facebook Odonate Larvae and Exuviae - the Nespresso Display Cube Capsule Dispenser, a 12cm perspex cube with good optical clarity. My previous attempt at underwater habitus shots of aquatic bugs (Twenty Thousand Leagues Under the Duckweed) was only semi-successful due to the iffy optical quality of the container I was using. Nespresso's cube is very sturdy and appears optically clear to the eye - to find alternatives, Google "acrylic display cube" and you'll come up with a whole range of sizes and prices. To put it to the test I used one of the long suffering Large Red Damselfly larva from my pond. 

The optical quality seems to be OK so it would be fine for larger aquatic species, and might be useful for terrestrial species too. What was immediately obvious is that a 12cm cube is too big for the species I am likely to photograph, so I struggled to get as much detail as I would have liked. I can solve the size problem with a moveable clear acrylic divider which can easily be shifted backwards and forwards to create the optimum photographic enclosure, although I haven't had chance to try this out yet.