Any pesticide that says it is "systemic" means that it goes into all parts of the plant/tree, including the fruit. Seems like not a good idea to me. I have had leaf miner in my citrus, but have discovered that when a tree is healthy and growing, it outgrows the miners. So I will dose the suffering tree with a hit of foliar fertilizer and that seems to work. For scale, which I have had on mangoes and on my charichuela, I just either smoosh them off with my fingers (small amount), or wash them off with soapy water on a paper towel (larger infestation.) Repeat in a few days to catch the ones that were too little to see the first time around. The biggest insect pest I have had here in Venus is the lubber grasshoppers. They are so big they will eat off a whole young shoot, by chewing straight through the stem. Makes me so mad!!!! Now in spring, I hold grasshopper patrols in the morning while it is still cool. The youngsters are black and roost together in the grass. I can kill hundreds with soapy water and my hands. If I am vigilant in the spring, I have almost no problems all summer. I have not seen the need for more powerful poisons than soapy water. That said, I have not tried things like low chill apples and peaches...I hear they need lots of insecticide.