What are the squiggly lines on my fruit tree leaves?
Homeowners are often perturbed by the sight of silvery lines running through their fruit tree leaves and in turn, causing the leaves to become crumpled.
This is caused by a bug called a leaf miner. Leaf miners are actually moths that will lay their eggs on the underside of the leaves of citrus trees. They are attracted to the new fleshy growth on your tree as when the larvae hatch, they burrow into the leaf- which creates the silvery line and the resulting crumpling.
Unfortunately, once these bugs are in the leaves, there is not point spraying anything as it won’t change a thing. The good news is, this primarily a cosmetic problem for the tree and will neither kill the tree nor damage the fruit.
Whenever a fruit tree starts to put out new growth – especially in the spring and early summer, both leaf miners and aphids will be attracted to this new growth. In order to try to keep these bugs off your tree, spray horticultural oil on the leaves to try to deter them. Always remember to NEVER spray when there are flowers on your tree and always spray late in the evening when the bees (that pollinate your trees) are less active. However, as mentioned above- this is primarily cosmetic and it is not absolutely necessary to spray.