Tuesday, March 27, 2012

Citrus Leafminer

What is happening to my citrus leaves? They look like something is tunneling through them?  
The tunneling damage is caused by the citrus leafminer, Phyllocnistis citrella.   It is not the same one that attacks tomatoes, cabbage and ornamentals like chrysanthemums. It is relatively new to the Hawaiian Islands. It was first noticed on Oahu in 2000 and now infests all the islands. 

The citrus leafminer is a tiny ½ inch silvery moth with a black spot at the tip of each wing.  It is the larval stage which lives inside young terminal leaves, feeding as they meander throughout the leaf. The moths are attracted to the new growth and once the leaves harden, the larvae will not be able to travel within the leaves. At the same time this pest came to Hawai`i, a tiny parasitic wasp came along with it.  Because of the presence of this wasp, citrus leafminer damage has been minimized. 

 What to do when the leafminer is present: avoid excessive pruning which will stimulate new flushes of growth. Even if the new flush of mature trees is heavily damaged and looks unsightly, the yields of most citrus varieties will be unaffected.