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Ministry of Agriculture, Food and Rural Affairs

Multi-Coloured asian lady beetles

Lady beetle adult Lady beetle larva Lady beetle pupa Click to enlarge.

Beginner

Scientific Name
            Harmonia axyridis

Identification
Eggs

  • oval-shaped eggs in clusters on the underside of leaves of plants where aphids are present

Larvae

  • soft-bodied “alligator-shaped" larvae with long legs, tiny flexible spines and are black in colour with red- orange markings

Adults

  • Vary in colour from pale yellow to deep red with multiple spots on the wing pads
  • 6-10 mm  long
  • Number of black spots on their wings anywhere from 0 to 19,
  • From few to many black spots on the wing pads
  • Immediately behind the head there is a small but distinctive "M" pattern when looking from wing pads to head

Damage

  • Multi-colored asian lady beetle (MALB) do not cause direct injury to berries; however, they are often found in the centre of clusters.  Their impact on grapes is the presence of compounds within their bodies called methoxypyrazines, which if released by the insect, gives off-flavours and odours to wine produced with fruit infested with MALB

Often Confused With
Other lady beetle species: no “M’ behind the head

Period of Activity
Pre-harvest through harvest.

Scouting Notes

  • Lady beetles are of no concern for vineyard health or grape quality, except near harvest time.
  • Begin monitoring for MALB several weeks prior to anticipated harvest date.
  •  Ten to 20 panels (throughout the block or cultivar) should be chosen in an average vineyard and at least five vines should be examined carefully at each panel.
  • These beetles can appear suddenly in vineyards so it is recommended to monitor daily for each cultivar in the last seven days before harvest.
  • For an outbreak year of Asian lady beetle, there are three key components:
    1. high aphid populations in host plants on which they feed
    2. a long warm fall switching to a period with cold night temperatures (less than 5-10C)  followed by warm days
    3. ripe fruit present when beetles start searching for overwintering sites.

Threshold
A threshold of 200-400 MALB per tonne of fruit has been suggested. MALB that are dead for 3 days or more do not result in taint, whereas live MALB or those dead for only 1 day may result in taint. However, many processors have much lower thresholds so please contact your buyer/processor directly to determine if controls are required to meet buyer needs.

Advanced

Scientific Name
            Harmonia axyridis

Identification
Eggs

  • oval-shaped eggs in clusters on the underside of leaves of plants where aphids are present

Larvae

  • soft-bodied “alligator-shaped" larvae with long legs, tiny flexible spines and are black in colour with red- orange markings

Adults

  • Vary in colour from pale yellow to deep red with multiple spots on the wing pads
  • 6-10 mm  long
  • Number of black spots on their wings anywhere from 0 to 19
  • From few to many black spots on the wing pads
  • Immediately behind the head there is a small but distinctive "M" pattern when looking from wing pads to head

Damage

  • Multi-colored asian lady beetle (MALB) do not cause direct injury to berries; however, they are often found in the centre of clusters. Their impact on grapes is the presence of compounds within their bodies called methoxypyrazines, which if released by the insect, gives off-flavours and odours to wine produced with fruit infested with MALB

Often Confused With
Other lady beetle species: no “M’ behind the head

Biology
MALB overwinter as adults in congregations in protected locations.  They emerge and mate in the spring and lay eggs near insect food sources.  Larvae feed voraciously for about 12 to 14 days on aphids, scale insects, and other soft-bodied invertebrates. The pupal stage lasts about 5 to 6 days. After emergence, adults can live as long as 2 to 3 years under optimal conditions.

MALB are normally beneficial insects, feeding mostly on aphids.  However, at the end of the summer, they start to prepare for winter by accumulating fat and sugar reserves. Adults move to vineyards, orchards, and other autumn ripening crops to feed on injured fruit. In the vineyard, grape clusters that have been injured due to physical splitting, yellow jackets or birds are an attractive option for MALB. The proportion of injured berries increases in the 2-3 weeks prior to harvest offering accessible feeding sites for MALB populations.

MALB is difficult to remove from clusters of grapes during harvest.. Adults tend to aggregate on clusters with injured berries just before harvest, and eventually they may be incorporated with the grapes during wine processing. When crushed, MALB releases a yellow fluid, that contains alkaloids and alkylmethoxypyrazines that affect wine flavour after MALB has been crushed along with the grapes. The flavour of the resulting wine may be tainted by these chemicals. If MALB are killed in the vineyard 3 days or more before harvest, they will not release the contaminating compounds when the fruit are processed.

Period of Activity
Mid August through pre-harvest and harvest completion late fall.

Scouting Notes

  • Lady beetles are of no concern for vineyard health or grape quality, except near harvest time.
  • Begin monitoring for MALB several weeks prior to anticipated harvest date.
  •  Ten to 20 panels (throughout the block or cultivar) should be chosen in an average vineyard and at least five vines should be examined carefully at each panel.
  • These beetles can appear suddenly in vineyards so it is recommended to monitor daily for each cultivar in the last seven days before harvest.
  • For an outbreak year of Asian lady beetle, there are three key components:
    1. high aphid populations in host plants on which they feed
    2. a long warm fall switching to a period with cold night temperatures (less than 5-10C)  followed by warm days
    3. ripe fruit present when beetles start searching for overwintering sites.

Threshold
A threshold of 200-400 MALB per tonne of fruit has been suggested. MALB that are dead for 3 days or more do not result in taint, whereas live MALB or those dead for only 1 day may result in taint. However, many processors have much lower thresholds so please contact your buyer/processor directly to determine if controls are required to meet buyer needs.

Management Notes
Try to minimize injury to berries that will produce compounds that may attract MALB.

Since aphids are the main food source for MALB, late season establishment of weeds should be suppressed in vineyards to reduce weed populations that provide sites for populations of aphids that are attractive to MALB. Some wineries have found that sorting fruit and the use of shaker tables before pressing may remove beetles.

Management with insecticides – Insecticides are used to control Multicoloured Asian lady beetle years when they are a problem. See OMAFRA Publication 360, Guide to Fruit Production - Chapter 5 Grapes : Recommendations for MALB in Special Sprays.   Consult your processor before spraying for MALB.