Holly Leaf Miner
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Holly Leaf Miner
 The Native Holly Leaf miner, Phytomyza ilicicola (Loew), as its name implies, is indigenous to the United States. It damages host plants by feeding on the leaf tissue between the upper and lower leaf surfaces with heavy infestations resulting in premature leaf drop.Susceptible Plants- Holly Life Cycle- The tiny, white, oval egg is laid in the newly emerging foliage. The larva (or maggot) is yellow and legless, and the pupa is oval and a reddish-brown color. The adult is a black and gray fly. Winter -Larvae over-winter in the leaf mines. Spring -The larvae pupate in late March or early April. The adult holly leaf miner flies emerge over a six-week period beginning when newly developed leaves appear on the holly in early May.
Summer- After mating, the female holly leaf miner fly lays her eggs by piercing the underside of the leaf with her ovipositor and placing the eggs in the mesophyll. When the eggs hatch, the larvae feed, creating new mines. There is one generation each year.
Symptoms- The holly leaf miner larvae feed so slowly that the damage may initially go unnoticed. At first, damage appears as a dark brown spot on the leaf, but as further feeding occurs, this turns into a long blotch by late winter. A heavy infestation may result in the majority of leaves being mined. Prior to egg laying, the adult female stabs the leaf with her ovipositor and both male and female adults feed on the sap that flows from the wound. This action leaves several small puncture wounds in the developing foliage. This is generally not a serious pest but the damage can be unsightly. Prevention and Control- Reduction of potential populations can be achieved if affected leaves that drop to the ground are collected and destroyed before the eggs of the holly leaf miner hatch. Bioligical Control- Leafminer Parasitoid Diglyphus isaea
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