More Springtail Watching (and a "new" bee)

27th January 2014
It's been quite a while since my last Blog post; this doesn't mean that my camera has been gathering dust though! I still seek out and photograph invertebrates most days but this time of year (Winter in the UK) there's a limited number of species available.

I've been continuing to monitor Collembola (springtails) in my local village churchyard and it has been interesting to see how the predominant species vary over time and how weather conditions affects different species and their apparent numbers. I thought I'd do bit of an update and show some of the highlight over the last couple of months.

I visit my local churchyard most days and during the winter, check out leaf-litter for invertebrates. Because i'm particularly interested in springtails; anything new to the location is very apparent because I'm quite familiar with the local springtail fauna. When I saw this Monobella grassei I was quite excited, because I'd never seen it anywhere before. I also recollected from the literature that it was generally confined to southern parts of the UK. Checking afterward I found that it had not been reported in Warwickshire before, nor anywhere else in the Midlands.

Monobella grassei is a member of the Poduromorpha springtails. These (like the Entomobryomorpha) are elongated, but generally not as bristly. They often have a "Michelin Man" appearance. This individual was 2-3mm in length.

I've also been experimenting with a modified macro setup for use with springtails. Many are only 1mm long or less and even with the MP-E macro lens at full magnification (5x), this is not enough. To get more "reach", I've recently started using a 1.4x tele-converter and a 36mm extension tube added to the lens. This gives ~8x magnification. I also use the Canon MT24-EX Twin Lite flash. This is fine without the "extension" (which reduces focusing distance), but cannot be angled down sufficiently when the lens is extended like this. It means that the front of the subject is sometimes insufficiently illuminated.

My brother-in-law (who also made my bee-hotel) offered to fabricate something for me to address this problem. There is a slotted plate that attaches to the lens' tripod ring (I never use a tripod). This allows backward and forward movement of the attchment. At the end of the plate is a semi-circular piece with a ball-jointed cold-shoe attachment at each flash unit. Recently, I've added a piece of translucent polypropylene sheet that fits between the top of the lens and the flash-heads, to improve light diffusion.

Having the extra magnification has allowed me to photograph even smaller subjects such as juvenile Sminthurinus springtails. The adults range from about 0.5mm to 1.0mm (depending on species). This very-early instar was less than 0.3mm and the image shows (heavily-cropped) oblique front and rear shots. At this stage they are virtually colourless or have a very pale purplish hue. I'm not sure if it's possible to determine the species this early. I suspect not.

These are very challenging to photograph. Even with a hand-lens, they are only just visible and then finding them through the camera viewfinder is somewhat hit-and-miss! Having a contrasting background helps.

Looking back to the warmer days of last summer, I've just had the identification of this little black bee verified. It's a male Sphecodes niger. This is a "new" species for me and is only the second Warwickshire record. Interesting too, is that the males are very rarely photographed in the wild, as live specimens.

Sphecodes niger is thought to be a cleptoparasite (cuckoo bee) of the more common Lasioglossum morio. Females enter the Lasioglossum nests and lay eggs in the brood chambers. The Sphecodes larvae eat the food stores (and often the host larvae) and emerge from the Lasioglossum nest the following season.

To me, this is a reminder that the "bee season" is not far away. My first sightings in 2013 were of the mining bee Andrena clarkella. This was on 4th March. I can't wait!

[Click on any image for a larger version]

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