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Ministry of Agriculture, Food and Rural Affairs

rose chafer

Rose chafer damageRose chafer adult and damageRose chafer matingRose chafer
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Beginner

Scientific Name: Macrodactylus subspinosus (Order: Coleoptera; Family: Scarabaeidae)

Identification

  • Belongs to the family of scarab beetles.
  • Adults feed on the flowers, fruit and leaves of various plants, and cause significant feeding damage to raspberry flower petals and buds.
  • Damage is usually localized and confined to a small area of the field.
  • Adult measures about 13 mm in length, has long, spiny legs, a light brown body covered with fine hairs and a black line down the middle of its back between the wing covers.
  • Head and underside of the beetle are dark brown or black.
  • Antennae are short and segmented, flat at the tip and enlarged into a knob.
  • Larvae are found in the soil, feed mainly on grass roots. .
  • Larvae measure about 19 mm in length, are C-shaped, white grubs with a brown head and 3 pairs of spiny brown legs.
  • Larvae can be distinguished by the parallel, rake-like arrangement of the short spines on the underside of the tip of the abdomen.

Often Confused With
Japanese beetle - damage
Raspberry fruitworm - damage
Raspberry sawfly - damage

Period of Activity
Adults are present from late May or early June until the end of June or early July. Females deposit their eggs in the soil.  Larvae hatch after 2 to 3 weeks. The grubs overwinter in the soil and pupate in early spring. Rose chafer infestations are most severe during bloom when the adults feed on flower petals and flower buds.

Scouting Notes
Look for holes or feeding damage on flowers and buds as well as the presence of the beetles themselves at the end of May and throughout June. Adult beetles can fly, so infestations can appear suddenly and from areas further away.

Thresholds
Not established.

 

Advanced

Scientific Name: Macrodactylus subspinosus (Order: Coleoptera; Family: Scarabaeidae)

Identification
The rose chafer, along with Japanese beetle, June beetle and European chafer, belongs to the family of scarab beetles. Adult rose chafers feed on the flowers, fruit and leaves of various plants, and in the case of raspberries they cause significant feeding damage to flower petals and flower buds. Damage is usually localized and confined to a small area of the field.

The adult beetle measures about 13 mm in length. It has long, spiny legs and a light brown body covered with fine hairs. A black line runs down the middle of its back between the wing covers. The head and underside of the beetle are dark brown or black. The antennae are short and segmented, flat at the tip and enlarged into a knob.

Rose chafer larvae are found in the soil where they feed mainly on the roots of grasses. The larvae are C-shaped, white grubs with a brown head and 3 pairs of spiny brown legs. They measure approximately 19 mm in length when fully mature. The dark contents of the gut show prominently through the cuticle at the end of the abdomen. Rose chafer larvae can be distinguished from other white grub larvae by the parallel, rake-like arrangement of the short spines on the underside of the tip of the abdomen. Each of the two parallel rows features about 8 or 9 spines.

Often Confused With

Japanese Beetle
Both rose chafer and Japanese beetle chew on plant tissues. Japanese beetle feeds primarily on fruit and leaves, causing skeletonization of the leaves. Rose chafer is active earlier in the season and feeds on buds and flower clusters.

Raspberry Fruitworm
Rose Chafer feeding damage usually results in the destruction of the whole flower bud or blossom. While leaf feeding damage may look similar to that of adult fruitworm, it usually occurs somewhat later in the season.

Raspberry Sawfly
Both insects occur in the early part of summer. Raspberry sawfly larvae only feed on leaves to create elongated holes, while rose chafer adults prefer flower petals and buds.

Biology
Rose chafers are more common in light, sandy soils with grassy sod or turf nearby. This beetle has one generation per year. The adults emerge from the soil in late May or early June and remain active for about 3 weeks. They usually appear in large numbers and mating begins shortly after they emerge. Females lay a single egg into the soil at a depth of about 10 to 15 cm. The eggs are shiny white, oval in shape, and about 1 mm long. It takes between 2 and 3 weeks for larvae to hatch from the eggs. The larvae feed on grass roots and overwinter in the soil below the frost line. They pupate in early spring. The next generation of adult rose chafers then emerges in the early summer.

Period of Activity
Adults are present from late May or early June until the end of June or early July. Females deposit their eggs in the soil and die shortly afterwards. Larvae hatch after 2 to 3 weeks. These larvae, or grubs, overwinter in the soil and pupate in early spring. Rose chafer infestations are most severe during bloom when the adults feed on flower petals and flower buds.

Scouting Notes
Look for holes or feeding damage on flowers and buds as well as the presence of the beetles themselves at the end of May and throughout June. Adult beetles can fly, so infestations can appear suddenly and from areas further away.

Thresholds
Not established.

Management Notes

  • Damage from rose chafer is often localized and occurs in the same spot year after year.
  • Ploughing or cultivating the soil can destroy larvae and pupae in the soil. However, controlling larvae in the field may not prevent adults from flying into the field.
  • Larvae feed on grass roots. If rose chafer infestations are a perennial, serious problem, avoid grass cover for row middles and cultivate the soil instead.