By Oddbillie
WALES,
United Kingdom 
Hi all
We bought some miniature fruit trees a few months ago and they seem to be doing nicely but noticed some red lines/veins on the leaves of all of them plus our cherry tree, which we've had for about 4 years now.
Just wondered what they were and if I need to do anything as I assume some sort of aphid or bug is the culprit?
Pic attached
19 Jul, 2015
Looks like leaf miner, though the trails are usually white not red. have a look at this link
http://www.planetnatural.com/pest-problem-solver/houseplant-pests/leafminer-control/
It says houseplants but it covers everything
20 Jul, 2015