Not sure what this insect is that's leaving squiggly lines on my leaves, like a 2 year old with a crayon! I've noticed it happening to my pepper and rose plants before, and now this is on my cucumber plant. I thought I had controlled it using neem oil, but this morning there was a noticeable increase in number of leaves with this pattern, as well as some discoloration. I sprayed with some neem oil again and some BT. They were fertilized yesterday. What can I do? Will it affect my cucumbers? It's a young plant so the fruits are just starting out.
Those are the larva of tiny black flies called Leaf Miners. There is a wasp Diglyphus isaea that thinks those larva are a tasty dish, call around to local nurseries to see if any are selling them....probably not any of the big box garden centers but you can try. Spraying pesticides around the plants may kill other beneficial bugs that will eat the flies so if you find the wasps don't do anymore spraying. Neem oil will affect the natural life cycle of the Leaf Miner flies and prevent the larva from becoming adults that will lay more eggs
@plantmom this link may explain also besides toni's advice https://www.discoverneem.com/neem-bees-beneficial-insects.html
The most effective treatment is a systemic insecticide called imidicloprid. Because the worms are inside the leaves they are well protected from most methods of control. Systemic treatments act through the vascular system of the plants themselves and become available to feeding insects in the cells where they feast.
