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Ministry of Agriculture, Food and Rural Affairs

White Apple leafhopper (WALH)

White apple leafhopper young nymph Older instar of white apple leafhopper – note wing pads White apple leafhopper adult (NYS Agric. Expt. Station, Geneva, NY) White apple leafhopper damage White apple leafhopper damage
Click to enlarge.

Beginner

Scientific Name
Typhlocyba pomaria

Identification
Eggs:

  • Less than 1 mm in length,
  • Cylindrical with tapering ends,
  • Creamy white in colour.

Nymphs:

  • There are five nymphal instars,
  • First and second instar- pale whitish with dull red eyes, and about 1.0-1.5 mm in length,
  • Third instar- wing pads and dull white eyes develop,
  • Fourth and fifth instar- similar in appearance to the third instar, but larger in size.

Adults:

  • Creamy white,
  • About 3 mm in length,
  • Hold their wings over their back when resting. 

Damage:

  • Pale green or whitish stipples on the leaf,
  • Fruit spotting- dark brown spots from deposited excrement.

Often Confused With

  • Potato leaf hopper nymphs- White apple leafhopper nymphs are differentiated from potato leafhopper nymphs by the way they walk when disturbed – white apple leafhoppers walk forward and backward, while potato leafhoppers walk sideways in a crab-like fashion.  Potato leafhoppers are more green in colour and their damage appears as leaf yellowing or chlorosis as well as cupping. 
  • Potato leafhopper adults- Potato leafhopper adults fold their wings across their back like a tent, while white apple leafhoppers hold their wings over their back when resting.  Potato leafhoppers appear in orchards later in the season (early summer).
  • Mullein bug nymph- mullein bugs have a more oval shaped abdomen and clubbed antennae, while white apple leafhoppers have a more elongated body.
  • Flyspeck- White apple leafhopper droppings can be confused with a fungal disease called flyspeck – affecting apples late in the summer. In contrast to leafhopper spots, flyspeck spots are charcoal gray to black in colour and cannot be washed off. Flyspeck usually occurs as a circle of evenly spaced spots – while leafhopper droppings are randomly spaced all over fruit.

Period of Activity
White apple leafhoppers are active from the end of pink until early summer, and again from mid-summer through harvest.

Scouting Notes
Check the undersides of 5 leaves from each of 20 randomly selected trees in an orchard block (for a total of 100 leaves). Select older and mid age leaves – located near the trunk area – for the first generation. Observe second generation leafhopper nymphs at arm’s length into the canopy, roughly midway into the radius of the tree. Examine leaves in the orchard by carefully observing the undersides for presence of nymphs. Newly hatched nymphs are difficult to see, so using a hand lens is recommended.

Initiate monitoring for first generation nymphs by late bloom or petal fall and continue for several weeks. Second generation nymphs are more difficult to monitor due to expanded foliage and a prolonged hatch beginning in late July and continuing well into August. White cast skins left over from nymphs moulting are often seen on leaves and terminals.

Thresholds
Low numbers of white apple leafhopper are not of economic concern. An insecticide treatment is only necessary when a threshold of 2-5 nymphs per leaf is observed in a 100-leaf sample.

Advanced

Scientific Name
Typhlocyba pomaria

Identification
Eggs: Approximately 1 mm in length, cylindrical with tapering ends and creamy white in colour.

Nymphs: There are five nymphal instars. Young nymphs (first and second instar) are pale whitish with dull red eyes, and about 1.0-1.5 mm in length. During the third instar, wing pads and dull white eyes develop. The fourth and fifth instar nymphs are similar in appearance to the third instar, but are larger in size. White apple leafhopper nymphs walk forward and backward when disturbed.

Adults:  Resemble nymphs but possess wings. Adults are creamy white, about 3 mm in length and hold their wings over their back when resting. 

Damage: White apple leafhopper damage causes stippling of the leaves and fruit spotting. Both nymph and adult white apple leafhopper insert sucking mouth parts into plant cells to remove the contents. This feeding leaves pale green or whitish stipples on the leaf where cells have been damaged. Leaf stippling reduces the photosynthetic area of the leaf, affecting fruit size, colour, maturity and winter hardiness of the tree. Leaf stippling appears more prevalent during the first generation in June and July.

As white apple leafhopper feed, they deposit excrement on fruit which dries into dark brown spots. These marks are unacceptable on apples destined for fresh market sales, especially cultivars with light-coloured skin. Fruit spotting is more prevalent during the leafhoppers’ second generation, beginning in August. Dried spots normally wash off with water and brushes on packing lines.
                
Often Confused With

  • Potato leaf hopper nymphs- White apple leafhopper nymphs are differentiated from potato leafhopper nymphs by the way they walk when disturbed – white apple leafhoppers walk forward and backward, while potato leafhoppers walk sideways in a crab-like fashion.  Potato leafhoppers are more green in colour and their damage appears as leaf yellowing or chlorosis as well as cupping. 
  • Potato leafhopper adults- Potato leafhopper adults fold their wings across their back like a tent, while white apple leafhoppers hold their wings over their back when resting.  Potato leafhoppers appear in orchards later in the season (early summer).
  • Mullein bug nymph- mullein bugs have a more oval shaped abdomen and clubbed antennae, while white apple leafhoppers have a more elongated body.
  • Flyspeck- White apple leafhopper droppings can be confused with a fungal disease called flyspeck – affecting apples late in the summer. In contrast to leafhopper spots, flyspeck spots are charcoal gray to black in colour and cannot be washed off. Flyspeck usually occurs as a circle of evenly spaced spots – while leafhopper droppings are randomly spaced all over fruit.

Biology
White apple leafhopper overwinters as an oblong egg about 1 mm in length, inserted beneath the bark and producing blisters on the twigs. Overwintering eggs are most often present on two-year-old wood, and are also found on wood three to five years of age. These eggs begin to hatch prior to bloom, and continue hatching through petal fall. Nymphs emerge and move to the foliage where they complete their development on the underside on a single leaf or cluster of leaves. Nymphs are seldom seen on the upper surfaces of leaves. Nymphs of the first generation are found on cluster leaves close to the main trunk or large limbs of the tree, and not often found on actively growing terminal shoots. Nymphs develop into adults in early summer. Mating usually occurs early in the morning and oviposition (egg laying) follows about 14 days later. Eggs are laid in the petioles, midribs and large secondary veins on the undersurface of leaves. The oviposition period lasts approximately three weeks and each female can deposit 50-60 eggs. The total lifespan of first generation adults is five to six weeks.

Second generation nymphs appear in early August and adults are present from mid to late August, until the first hard frost. This second generation is less synchronized and more difficult to control. In Ontario, there are two generations per year.   

Period of Activity
White apple leafhoppers are active from the end of pink until early summer, and again from mid-summer through harvest.

Scouting Notes
Check the undersides of 5 leaves from each of 20 randomly selected trees in an orchard block (for a total of 100 leaves). Select older and mid age leaves – located near the trunk area – for the first generation. Observe second generation leafhopper nymphs at arm’s length into the canopy, roughly midway into the radius of the tree. Examine leaves in the orchard by carefully observing the undersides for presence of nymphs. Newly hatched nymphs are difficult to see, so using a hand lens is recommended.

Initiate monitoring for first generation nymphs by late bloom or petal fall and continue for several weeks. Second generation nymphs are more difficult to monitor due to expanded foliage and a prolonged hatch beginning in late July and continuing well into August. White cast skins left over from nymphs molting are often seen on leaves and terminals.

Thresholds
Low numbers of white apple leafhopper are not of economic concern. An insecticide treatment is only necessary when a spray threshold of 2-5 nymphs per leaf is observed in a 100 leaf sample.

Management Notes

  • Leafhoppers and other sucking insects can transfer diseases (such as fire blight) from one plant to another, however the importance of leafhoppers in the dispersal of this bacterial disease is unknown.
  • In heavily infested orchards, white apple leafhopper adults can fly up in clouds into pickers’ eyes, ears, noses and mouths. This irritation can reduce worker efficiency and pose a safety threat if workers are distracted when operating equipment or climbing ladders.
  • There are a few parasitoids or predators that attack white apple leafhopper, but none provide biological control. Mullein bugs are sometimes observed feeding on leafhopper nymphs.
  • Insecticides are most effective on younger nymphal stages during the first generation, and second generation control is not often required. Where late season populations surpass threshold levels, insecticide timing can be difficult due to the extended hatch.
  • The white apple leafhopper is resistant to organophosphate insecticides.
  • For recommended materials, see OMAFRA Publication 360, Guide to Fruit Production - Chapter 3 Apples (PDF) or Apple Calendar only (PDF) :