Pacific Northwest Insect Management Handbook

Greenhouse ornamentals-Leafminer

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Liriomyza trifolii

Pest description and crop damage Leafminer adults are small flies, the most common is Liriomyza trifolii, which is about 0.125 inches long and black and yellow. The larvae are legless maggots. Mines from larval feeding in the leaves can make plants unmarketable.

Biology and life history The adult leafminer inserts its eggs into the leaf material. The egg hatches and the small white maggot mines within the leaves. The maggots then drop to the floor or substrate to pupate. Leafminers can complete a generation in about two weeks at 95°F. There can be many life cycles per season.

Scouting and thresholds Leafminers can be monitored with yellow sticky cards and looking for direct sting or oviposition damage on the leaves.

Management-biological control

Natural enemies include:

  • entomopathogenic nematodes (Steinernema feltiae)-Foliar applications in greenhouses
  • parasitic wasps (Dacnusa sibirica)-Commercially available. Used for management of Liriomyza spp.
  • parasitic wasps (Diglyphus spp.)-Commercially available. Used for management of Liriomyza spp.

Management-chemical control

  • abamectin (Avid 0.15 EC) at 0.009 lb ai/100 gal (8 fl oz). REI 12 hr. Apply at 7-day intervals.
  • acephate (Precise, Orthene TR) at 0.024 lb ai/1,000 sq ft broadcast (0.6 oz). REI 24 hr.
  • acetamiprid (Tristar 30SG) at 0.5 lb ai/100 gal (2.7 oz). REI 12 hr.
  • azadiractin (Azahar, Azatin XL)-Insect growth regulator. Some formulations are OMRI-listed for organic use.
  • bifenthrin (Talstar) at 0.335 to 0.67 lb ai/1,000 sq ft. REI 12 hr. Restricted use pesticide.
  • bifenthrin, clothianidin (Aloft)-Various formulations, some RUP.
  • canola oil, pyrethrins (Pycana)-Dormant, pre-bloom and summer use 1% = 1.5 to 3 gal/1,000 sq ft; 2% = 1.5 gal/100 sq ft.
  • carbaryl (Sevin) at 1 quart/A or per 100 gal (3/4 fl oz per 1,000 sq ft).
  • chlorantraniliprole (Acelepryn) foliar, bark and soil treatment
  • chlorpyrifos (Vulcan) at 1/12 to 1/6 fl oz per gal on 0.5 to 1 pint per 100 gal, no more than 2.8 quarts per acre/year.
  • clothianidin (Arena)-Post bloom applications only, 2 to 3 oz/100 gal spray solution or 4 to 6 oz/A.
  • cottonseed oil (Furious) at 22 to 33 fl oz/A or 3 fl oz/gal for 1,000 sq ft. WA only.
  • cyantraniliprole (Mainspring) at 2 to 8 fl oz per 100 gal (0.6 to 2.4 ml per gal). Reapply on a 7- 14-day interval.
  • cyclaniliprole (Sarisa) at 16.4 to 27 fl oz (0.054 to 0.090 lb. ai/100 gal) or 16.4 to 27 fl oz (0.054 to 0.090 lb. ai/A)
  • cyclaniliprole/flonicamid (Pradia) at 10 to 17.5 fl oz/100 gal.
  • cyfluthrin/imidacloprid (Discus N/G) at 0.063 lb ai/100 gal foliar; 0.009 to 0.014 lb ai/1,000 ft soil. REI 12 hr.
  • cyhalothrin-gamma (Scion) at 1.3 to 4.4 fl oz/100 gal or 39 to 132 mL/100 gal.
  • cyromazine (Citation) at 2 oz ai/100 gal. Apply to the larval stage. REI 12 hr.
  • deltamethrin (D-Fense Dust) at 8 oz product per 1,000 sq ft or as a thin layer.
  • diazinon (Diazinon 50W) at 1.0 lb/100 gal water; spray when first appear.
  • diflubenzuron (Adept) at 0.5 oz ai/100 gal soil. Apply to the larval stage. REI 12 hr.
  • dimethoate (Dimate 4E)-Rate specific to host species.
  • dinotefuran (Safari 20SG) at 0.1 to 0.2 lb ai/1,000 ft sq; 0.05 to 0.1 lb ai/100 gal. REI 12 hr.
  • emamectin benzoate (TREE-age)-Application rate dependent on DBH.
  • fenpropathrin (Tame 2.4EC) at 0.1 to 0.2 lb ai/A (5.3 to 10.7 fl oz). REI 24 hr.
  • flupyradifurone (Altus) (citrus leafminer suppression) at 14.0 fl oz/A.
  • geraniol, peppermint oil, rosemary oil (Keyplex Ecotrol) at 16 to 48 fl oz/100 gal; spray at first appearance, every 5-7 days
  • imidacloprid (Marathon II) at 0.027 oz ai /100 gal foliar. Drench and irrigation are permitted. REI 12 hr.
  • Isaria fumosoroseus (PFR 97) at 0.175 to 3.5 lb ai/100 gal foliar. REI 4 hr.
  • lambda-cyhalothrin (Scimitar GC) at 0.013 to 0.043 lb ai /100 gal. REI 24 hr. Adult leafminers only.
  • malathion (Malathion 8 Aquamul) at 1.25 pints in 100 gal water as a dilute spray.
  • methoxyfenozide (Invertid, Intrepid 2F, Inspirato 2F and others)-Application varies by product, see label for application rates.
  • mineral oil/petroleum distillate (Biocover LS)-Some formulations are OMRI-listed for organic use.
  • naled (Dibrom 8)-Application varies by application type and crop.
  • neem oil (Nimbiosys) at 1 to 2 pints/A at 0.5% concentration of neem oil in water.
  • novaluron (Pedestal) at 0.039 to 0.052 oz ai/100 gal. Apply to the larval stage. REI 12 hr.
  • permethrin (Pounce 25 WP) at 6.4 to 12.8 oz (0.1 to 0.2 lb active) per 100 gal water.
  • permethrin, piperonyl butoxide (Drop Dead)-Spray at a distance of 12 to 15 inches
  • phosmet (Imidan) at 0.75 to 1 lb per 100 gal. (0.5 to 0.7 lb ai).
  • phosphine (Eco2Fume Fumigant Gas)-RUP between 0°C and 25° C. Minimum of 200 ppm/0.88 lb of product to 3,625 ppm or 16.0 lb. Do not fumigate at max rate.
  • piperonyl butoxide, pyrethrins (Stryker, Pyrenone Crop Spray, Pyronyl Crop Spray)-Various application rates.
  • potassium laurate (M-Pede)-Use a 1 to 2% solution
  • pyrethrins (Tersus) flower and foliage plants at 13.07 fl oz concentrate with 100 gal water, apply at 3 gal/1,000 sq ft.
  • pyriproxifen (Distance) at 0.054 to 0.081 lb ai/100 gal (8 to 12 fl oz) foliar. Apply to the larval stage. REI 12 hr.
  • s-kinoprene (Enstar AQ) at 0.012 to 0.024 lb ai/10,000 sq ft. REI 4 hr.
  • sodium borate (Prev-Am) fungicide + insecticide-Label rates vary by application type
  • soybean oil (Golden Pest)-Dilute 1 to 3 gal per 100 gal water.
  • thiamethoxam (Flagship 25W)-Separate application rate recommendations depend on application type.

Kaur, N. (Ed.). 2024 Pacific Northwest Insect Management Handbook.
© Oregon State University.

Use pesticides safely!

  • Wear protective clothing and safety devices as recommended on the label. Bathe or shower after each use.
  • Read the pesticide label—even if you’ve used the pesticide before. Follow closely the instructions on the label (and any other directions you have).
  • Be cautious when you apply pesticides. Know your legal responsibility as a pesticide applicator. You may be liable for injury or damage resulting from pesticide use.

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