Saturday, 4 October 2008

The mining boom

I'm resigned to being chained to the computer for the next few weeks, which means that my only foray into the natural world will be in my back yard — where something's been scribbling on leaves.

Leaf miners are hard at work, excavating tunnels in the tissue between the upper and lower layers of cuticle. They're chewing their way through the leaves, stuffing their little faces with plant cells or tapping the sap from the veins until they're ready to pupate. That's the life of a larval insect: eat, poo, grow. Oh, and avoid predators, of course. And people with cameras.

Many types of insects have larvae that mine leaves. I'm not sure what these are — beetles, flies, wasps or moths. I might stick a plastic bag around one of the leaves to see what emerges. Because most of these insects have short life cycles, it shouldn't be too long before they pupate and metamorphose into the adult stage. Unless they've been got at by parasitoid wasps, that is.

Leaf miners are used for biological control of some weed species. The herringbone leaf miner fly (Ophiomyia camarae) and a couple of beetle species (Uroplanta girardi, Octotoma scabripennis) have been brought in from South and Central America to give invasive lantana (Lantana camara) a hard time. A species of leaf mining moth (Dialectica scalariella) feeds on Paterson's curse (Echium plantagineum). In these cases, the insects don't kill the target plant but slow down its growth and reduce seed production. The leaf miners in my garden have had no noticeable effect on the weeds.


budak said...

did you squeeze that bugger out of his tunnel?

Snail said...

I tore the leaf so I wouldn't damage the little bugger. Well, damage it beyond evicting it from its home.

Mosura said...

Fascinating and I'm amazed you managed to extricate one! I went looking for mines in the garden a couple of weeks ago but could only find old ones.

Bagging one up is a good idea but maybe you could use a net bag - the plastic ones tend yo get all wet from the transpiration.

There are some Lepidopteran miners which only mine in the early instars and move onto the surface and eat whole leaves.

Snail said...

I've abandoned the placcy bag but in doing so, knocked off the leaves, so they're all in a big plastic bug container.

Have taken a few more pics. It's a fly!

sarala said...

Leaf miners. I never knew so much about such ugly creatures. I wonder if my turtle would eat one. It's no more gross than the mealworms I'm feeding her.

Snail said...

Sarala, I don't think your turtle would even see these little critters --- they are only 2 - 3 mm long! I put one on my finger tip to take a photo and it looked as though the insect was sitting on a ploughed field!