Commercial Horticulture > Vegetable > Vegetable Insect Pests > Insect Pests of Tomatoes
 Name Thumbnails  Plant Injury Sampling method & economic threshold (ET)

Tomato aphids (potato aphid, green peach aphid, etc.)

 

Leaves, stem (early season pest)
  •  Record the number of leaves with wingless or nonmigratory aphids present.
  • Watch for ant and ladybettle populations on plants as a sign if infestation.
  • ET = 50% leaves have aphid in any plant stage (UK)
Flea beetles (tobacco flea beetle, pale striped flea beetle)   Seedling leaves (defoliation is threatening on a <6 inch plant), 3 -4 generations can damage a lot of crop  
  • Estimate the level of defoliation (shot-holes) on 10 plants
  • Sample adults with sweep net during mid-morning hours (when beetles come up to bask in the sunlight) and relate it with foliar injury
  • Observe natural enemy populations in field (e.g., bigeyed bug) - abundance of these predators could indicate pest population.
  • ET = 5-10% foliar injury early in season (UGA), 25-30% foliar injury in midseason (UK)
 Colorado potato beetle    Seedling leaves, defoliation less threatening on mature plants.  This insect has shown insecticide resistance in some areas.
  •  Beetle injury first appears on field margins in the form leaf skeletonization.
  • Scout more intensely in short crop (<6 to 10 inches)
  • Adult beetles and larvae are easily seen on plants. Estimate number of insects on 10 plants at each location.
  • ET = 5 beetles per 10 plant in short crop (UK) or 10% defoliation (UGA)
 Tomato fruitworm    Key insect of tomato and many other crops.  Feeding on fruit and can severely reduce yields. Prefers green fruit and the stem end.  Larvae feeds with part of it's body inside the fruit.  This insect has resistance to some insecticides.
  •  Pheromone traps can be used to monitor moths. Pheromone traps do not indicate actual crop injury, but can indicate the suitable time of control of this insect.  
  • Scout for egg masses or larvae during fruit set.  Larvae have four pairs of prolegs and feed near the top of fruit.
  • ET = 7 moths/pheromone trap or eggs present on foliage (UK).  Threat is high if fresh feeding damage occurs 1 per plant at green fruit stage.
 Stink bugs    Causes serious damage to ripening fruits (whitish-yellow spots or rings under the skin of ripening tomatoes)
  •  Try using a sweep net to catch adults mid-morning
  • Scout intensively when fruit formation begins. Count insects on 10 plants randomly across a field.  Sample more plants in large fields (>10 acres).  On green fruits, black specks could indicate stink bug injury.
  • ET = 0.25 stink bugs per 10 plants at green fruit stage (UK)
 Cabbage looper    Leaves are damaged but fruits are spared (minor pest)
  •  Study the leaves directly from 10 plants per location and look for larvae (cabbage looper larvae have two pairs of abdominal prolegs)
  • Look for fecal pellets on leaves.
  • ET = 5 looper larvae per 10 plants at any plant stage (UK), or defoliation greater than 20%
Wireworms (potato wireworm & other species) This can be a major early on tomato because it severs seedlings while living at the soil-air interface. Beetles are very attracted to grassy crops or weedy landscape.
  • Deploy germinating seed bait stations (wheat-corn mixture) at several locations in fields with a history of wireworm attack. 
  • Use soil cores (sample around small tomato seedlings/transplants), and wash the dirt to recover larvae.  Use larval size and number as an indicator of life stage and insect pressure.
  • ET = 1 wireworm per seed bait (average from several baits across a field)

Image sources:  Univ. of Kentucky, University of Georgia, North Dakota State University, University of Florida