This is taken from the University of Arizona

Situation: Primarily an Asian pest, citrus leafminers were first discovered in Florida in 1993. These moths rapidly became a significant problem, with infestation rates of up to 90% of orchards in some areas in Florida in the year of introduction. By 1995, the citrus leafminer was discovered in Texas, Central America, western Mexico, and several Caribbean islands. The leafminer has been found in the Imperial Valley and across the border in Mexicali, Mexico.

Damage: Larvae of citrus leafminer form serpentine mines in leaves and fruit of citrus. Grapefruit, lemon and lime are most susceptible to damage but the leafminer attacks all varieties, as well as over 20 different plants belonging to the citrus family Rutaceae. Mines are characteristized by a central line of frass (red arrow in figure below), which can be used to separate them from mines of the native peelminer. The citrus leafminer only infests young flushing foliage and lays its eggs on upper and lower surfaces of leaves less than half an inch in length. Pupation occurs in folds on the edges of leaves. Citrus leafminer rarely attacks fruit. Leafminers have a short developmental time andas many as 6-13 generations per year can be expected depending on foliage flushing cycles and temperature. Infestation levels of 1-3 mines per leaf occur in Australia. In Florida, which has a much wetter climate, infestations of 15-20 miners per leaf are common.

Economic Impact: Economic losses due to the citrus leafminer include 1) increased costs for protecting nursery trees and young non-bearing citrus, 2) reduced sales to home gardeners, and 3) increased orchard production costs, either directly, through the use of pesticides (largely ineffective), or indirectly, through treatments that disrupt biological control and Integrated Pest Management programs. Except on limes, the loss of yield on mature trees because of foliage damage has not been demonstrated.

Distribution: Citrus leafminer was relatively unknown until the mid-1970's, when in Australia, it was first noticed as a pest. It was first described in 1856 and first reported from Australia in 1918 and South Africa as early as 1908. Since it has achieved pest status, its range has rapidly expanded worldwide to include the Mediterranean, Africa, Central America and the United States.

Control: Enhancement of natural enemies, especially parasitic wasps, is considered the most effective means of managing infestations of the citrus leafminer on older fruit bearing citrus. Two poly-embryonic parasitoids are considered to have potential for effective control. 1) The encyrtid wasp, Ageniaspis citricola, is a specific parasite and will be imported. In the pupal stage, the wasp forms a chain of 2-7 brown cocoons. 2) The native eulophid wasp, Cirrospilus coachellae, which attacks the citrus peelminer, is expected to shift to the leafminer. This parasite forms a series of 2-7 naked black pupae in the mine. Other species of native eulophid wasps also are expected to shift to the leafminer as populations increase.

Laaz I've read in some forums where people (mostly container growers), pull the leaves infected by leaf miners off the tree. I have often wondered if this in fact did more harm than good. If one pulled all the inected leavess off a small container tree, it would surely greatly reduce the ability of the tree to produce photosynthates (sugars) which is the food source for the tree. I wonder if this helps or hurts? I also heard that most commerical growers do nothing at all. - Millet

Millet,

If I were to pull off all my LM-infested leaves, I would be left with some pretty pitiful sticks! LOL! I have been using Ferti-Lome with some success so far. Interestingly, the leaf miners seem to have left my satsuma alone so far.

I luckily only have a minor problem with LM, I guess I have enough Lizards around to help eat the moths. I do just rip the leaves off that have trails, but from what I understand it is only a vanity thing. There would have to be ALOT of LM on any one plant to hurt it. Just my 2 cents worth.
Darren

as a Non Pesticidal person or should i say one who is afraid of chemicals LOL ...

I love Dawn dishwashing soap to smother the darned things and it works

i also Bathe my dogs (Puppies) with dawn to kill fleas at a week or 2 old since we here in oregon on the coast are loaded and advantage isnt the best deal and frontline is about 4 miles away LOL ...


make a spray and delute it with 3 tea spoons of dawn or even use your dish soap water from washing .. also if it gets trally thick on the leaves add a 1 table spoon of Bleach...

Im sorry but i just dont trust chemicals and i am allergic to bleach so why do they say you cant be ?

Ive had to eat veggies and fruits i grow myself im going on my 5th surgery to have a tumer removed from my Left Side .. if the lable says it will kill a bug wear a mast cause its surly not going to do you any good OK Tammy

Leaf miners really gave me grief in 2005 on my lemon and lime trees. As soon as they stop blooming I'm going to spray them with hort oil again in an attempt to forestall the things this year. I'm getting excellent growth these last two months so I want to safeguard it.

.....Alan.

Last year I saw the kind of leaf miner that leaves a central trail
of frass for the first time in Orange County.

A few days ago I found two leaves with
leaf miners on my Honey (Murcott) mandarin.
Today, after reading this
series of posts, I looked again and
found 8 leaves infected with miners.

The tree is about 3 feet tall, on
"Flying Dragon", and has a hundred new leaves.
So I pinched off and crushed the infested leaves and
dumped them in a garbage bag.