Green Shieldbug development

On 07.06.2024 (Day0) I spotted a Green Shieldbug, Palomena prasina, laying eggs outside my kitchen window:

By Day2 post-laying, the little perforated lids out of which the nymphs would eventually pop were already visible:

And then, not much happened. The weather was cold and the eggs developed a little more slowly than they might have done otherwise. Then, on Day16 after laying, tiny red eyes were visible through the shells:

Day18 - great excitement, the eggs hatched and the nymphs emerged:

24 hours after hatching the first instar nymphs had hardly moved, possibly waiting for their first moult to disperse?

At this point I moved ther nymphs to a less exposed spot where they will have a better chance of survival. Bon chance, mes petites. 

  

Killer Shrimp!

According to the media, any invertebrate new to the UK is a Killer! (complete with exclamation mark). 

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!

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