Holly Leafminer (Phytomyza ilicicola)
GDD Window (base 50): 147-265
Overview:
- Overwinter as yellow larvae, 1.5 mm long
- Eggs hatch into tiny maggots within the leaf mine, causing the most damage in early spring
- Adults are small, 0.8-1.6 mm long black flies
- Maggots pupate in the spring
- Adults emerge from leaves in May, mate, and female deposits eggs in slits on the underside of new leaves
- One generation per year
- Mines are narrow in the fall but expand during the spring, causing leaves to have yellow serpentine or blotch mines
- Causes premature leaf drop, defoliation, leaf growth stunting and distortion
- Host plants: American holly and cultivars
Management:
Cultural Practices:
- Natural predators: parasitoid wasps, green lacewings, spiders
- Reduce plant stress
- Avoid overuse of insecticides
- Pull off and destroy mined leaves before May in light infestations on small hollies
- Sticky traps to monitor for adults
- Destroy prematurely dropped leaves
Materials:
- Contact insecticides:
- Avermectins [6]: abamectin
- Pyrethroids [3]: –thrins
- Will only suppress adults
- Carbamates [1A]: carbaryl
- Will only suppress adults
- Systemic insecticides: (larvae only, ~June application):
- Organophosphates [1B]: acephate
- Neonicotinoids [4A]: imidacloprid, dinotefuran
- Considerations:
- Will harm non-target species
Biorationals:
- Neem oil
- Insecticidal soap
- Spinosyns [5]: spinosad
Disclaimer – Materials do not cover all possible control scenarios and are intended for licensed professionals. Tradenames do not imply endorsement and are used as examples. You must strictly follow the label for each compound prior to use. Rutgers is not responsible form is used materials or damages thereof. The label is the law. Labels will provide detailed information on use and restrictions. Additionally, application intervals, compatibility, surfactant use, PHI, PPE, important and other key information is described in detail. Always discuss treatments with your local agents. Note: Neonicotinoids can only be legally applied in commercial agriculture settings by licensed applicators. Guidelines and recommendations made in this presentation are specific to the state of New Jersey.