13. Coronavirus and leaf miners

13. Coronavirus and leaf miners

So here's the problem, this blog is about what can be found on the Campus grounds.

But from February I haven' actually been at University much.

There was a lecturers strike so lectures were cancelled Monday to Wednesday, and quite a few Thursday and Friday lectures too, then when the strike finished UEA was closed for the Covid -19 outbreak and may remain shut for the foreseeable? 

So I not going back to Uni for a while, but the blog needs to continue...blogging about what is seen on campus when we are not on campus, for public safety reasons, is clearly impossible.

So from now on I'll be blogging just the same, but away from campus. 

The last thing I saw on Campus before Uni' was shut down was the very common and humble Holly Leaf Miner Phytomyza ilicis which is a fly in the Agromyzidae family.

Here's my last photo from campus followed by some pics of blue tits

What you can see here is the leaf miners 'mine' inside is the lavae of the fly (maggot) chewing a tunnel (or mine) between the leaf upper and lower surface.

The leaf miner fly lays an egg inside the leaf, on the underside where the petiole (stalk) joins the leaf, the maggot hatches and burrows up the midrib and then randomly around inside the leaf, if lucky you may see a mine that follows a less meandering path than this, and when that happens you would notice the burrow getting wider and wider as the maggot gets bigger. Sadly this one when round and round and backwards and forwards up the same mine so the size increase wasn't noticeable.

The holly leaf miner is host specific, meaning it always lays it's eggs in Holly Ilex aquifolium leaf, once full grown it will chew an exit hole in the surface >1mm across and pupate, and crawl out through the hole as a fully developed and winged fly (UK fly mines 2016).

The leaf minor doesn't seem to harm the Holly, even a severe infestation only accounts for 1 out of 6 leaves and the holly can cope with the loss is seems.

The leaf minor grub itself does get predated on a lot by other though, Chalcid and brachonid wasps lays eggs in about 3% of the leaf minor grubs and blue tits eat about 40% of the grubs, leave classic triangular holes in the leaf surface where they have ripped out the grub.

The first two pictures show where blue tits have extracted the grub. The last picture was where I had carefully peeled back the top surface with a scalpel to reveal the larvae itself, app' 2 mm long and 1 mm across. The leaf minor it is the tiny orange grub next to my thumb, which doesn't seem like much of a meal for a tit, but clearly it is worth the effort otherwise they wouldn't eat them. 

However one could use the same argument with me eating a single peanut, there would be a rough equivalence of size between a blue tit and a leaf minor larvae and me and a peanut. But if I ate 50 peanuts that's enough calories to keep me going for a few hours, I imagine 50 grubs is enough for a tit too.

The adult fly itself is only 2-3 mm in length, no biiger that the tiny fruit flies that float around bananas skins or potato peelings in the waste bin at your home.

Picture of a Tit below (come on...behave)

Eurasion blue tit Cyanistes caeruleus on holly Ilex aquifilium looking for Phytomiza ilicis possibly?

UK Fly Mines (2016) The leaf and stem mines of British flies and other insects. Available at: http://www.ukflymines.co.uk/Flies/Phytomyza_ilicis.php (Accessed on; 22/02.2020)