30 Days Wild | Day 8

For today’s #30DaysWild challenge I decided to focus on finding and identifying some leaf miners. ‘What exactly are leaf miners?’ I hear you ask…well this blanket definition covers a diverse range of specialist invertebrate species whose larvae grow and develop between the laminae of leaves. Feeding on the tissue of plants, the most common groups of insects to perform this intriguing function are moths (lepidoptera) and flies (diptera)

Bramble leaf mines
The mines of Stigmella aurella on Bramble leaves – one of two very common species to utilise this ubiquitous food resource

Leaf miners can be very specific to their host plant species, which means identifying the culprit responsible for such funny-looking patterns and trails can be straight forward: if you know the plant species, you’re likely to know the leaf miner species!

It’s not always that simple, though, as a variety of different leaf miners can feed on the same plant and many are polyphagous (feeding on several different species); instead, you can look at the specific mine pattern, the time of year, and the pattern of dropping deposition in the tail (frass) to identify the species. A very handy website for identifying mines is www.leafmines.co.uk

Nipplewort 2
A rather well-mined leaf of Nipplewort (Lapsana communis) by one of two fly species, either Chromatomyia horticola or C. syngenesiae

Whilst walking around the island today I was keeping an eye out for some mined plants, and discovered no fewer than seven different species inflicted by the action of these unique larvae. Here are some of the ones I found…

leaf mines-001

Most of the mines I found were created by Diptera larvae (flies), as opposed to those of lepidoptera (moths). A useful way to tell the immediate difference is that Diptera mines tend to have a twin-line of droppings, whereas moth larvae deposit just a single trail of frass.

I collected some of the mined leaves and the plants they belonged to so as to help my botany identification! A large number were Ranunuculus plants in the Buttercup family, with shared polyphagous mining species. This was the list I managed to produce after using the British Leaf-mining website as an ID guide:

  • Aulagromyza cornigera on Honeysuckle leaves (Lonicera periclymenum)
  • Amauromyza flavifrons diptera blotch mines on Red Campion leaf (Silene dioica)
  • Phytomyza ranunculivora on Creeping Buttercup (Ranunuculus repens) and Meadow Buttercup (R. acris)
  • Phytomyza ranunculi on Lesser Spearwort (Ranunculus flammula)
  • Phytomyza pastinacae/spondylli on Hogweed (Heracleum sphondylium) – identical two species only separated by adult dissection
  • Stigmella aurella on Blackberry (Rubus fruticosus)
A macro shot of the venation of a Nipplewort leaf, with a sneaky Diptera leaf miner trail at the lower edge of the image (can you see the double-dot pattern of frass?)

So when you’re next out and notice weird squiggly lines adorning plant leaves, why not take a picture or a sample, and try do a bit of detective work to figure out the creature responsible for it’s creation? It’s great fun!

On an overall misty, sunny, rainy, windy, warm, and bright day (yep, we had a real mixture!) I had some fun time watching this enthusiastic male Northern Wheatear song-flighting in one of the bays…

…and came across a colour-ringed Whimbrel which we ringed back in autumn 2016. It’s stuck around until now and is even in mid-primary moult now – a semi resident bird! It looks set to be a busy day tomorrow: we’ll be shifting everyone’s luggage for an early visitor  changeover day ahead of an incoming storm at the weekend; and we’ll also be vaccinating half of our 400 lambs!


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