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Beginner

Scientific Name: Popillia japonica (Order: Coleoptera; Family: Scarabaeidae)

Identification

• Beetles feed on foliage, causing shredded and skeletonized leaves, especially on the upper parts of canes.
• Large blocky insects about 13 mm in length.
• Shiny, metallic green appearance with coppery brown wing covers.
• Prominent spiny legs and clubbed antennae.
• Six tufts of white hairs on each side of the abdomen.
• Larvae are found in the soil and are C-shaped white grubs with prominent spiny legs and a brown head capsule.

Often Confused With
Raspberry Sawfly damage
Raspberry Fruitworm damage
Rose Chafer
White grub larvae: June beetle, European Chafer

Period of Activity
Adult beetles emerge in late June and early July and can remain present in brambles until early September. Feeding damage is most pronounced in fall-bearing varieties when adult beetle populations peak. The beetles are especially active on warm, sunny days.

Scouting Notes
Look for feeding damage on leaves in late June and July as well as for the presence of the beetles themselves. Inspect plantings weekly as beetles can fly great distances and may travel from their over-wintering sites to the raspberry field to feed. Male and female beetles may also be lured to traps by Japonilure, which is an artificial lure containing a sex hormone and floral volatiles.

Thresholds
None established.

 

Advanced

Scientific Name: Popillia japonica (Order: Coleoptera; Family: Scarabaeidae)

Identification
Japanese beetle adults cause feeding damage on raspberry leaves, flowers and fruit. They feed on leaves and heavy infestations may lead to the skeletonization of leaves, especially those on the upper parts of canes. The adults also damage ripe fruit by burrowing into them to feed. The beetles are especially active on warm, sunny days.

The adults belong to the same insect family as European chafer, rose chafer, and June beetles. They are large blocky insects about 13 mm in length and have a shiny, metallic green appearance with coppery brown wing covers. They have prominent spiny legs and clubbed antennae. Six tufts of white hairs on each side of their abdomen are the distinctive feature of this beetle.

Japanese beetle larvae are found in the soil. Larvae are C-shaped white grubs with prominent spiny legs and a brown head capsule. They can be distinguished from other species of white grubs by the pattern of spines or rasters on the underside of the last abdominal segment. Japanese beetle larvae have 6 or 7 pairs of spines arranged in 2 rows, in a V-shaped pattern. They can measure up to 2.5 cm in length when fully mature.

Often Confused With
Although adults are easily observed and identified, the damage they cause can be similar to that caused by other pests.

Raspberry Sawfly
The feeding damage to leaves may look similar; however, Japanese beetle infestations often lead to complete skeletonization of the leaves. Sawfly larvae, which cause leaf damage in raspberries, are also present earlier in June, whereas Japanese Beetles emerge more so towards the end of June.

Raspberry Fruitworm
The feeding damage is similar, but fruitworm adults feed on leaf buds which leads to symmetrical, lengthwise feeding holes on developing leaves.

Rose Chafer
This insect emerges earlier than the Japanese beetle and feeds more on the flowers, flower buds and young leaves.

White grub larvae: June beetle, European Chafer
Japanese beetle larvae can be distinguished from other white grub larvae by the pattern of rasters or spines on the last abdominal segment.

	Japanese Beetle	Rose Chafer	European Chafer	June Beetle
Adults active	Late July – August	June	Mid-June to mid-July but variable	Late May to early June
Adults feed on fruit	Yes	Yes	No	No
Larvae: White grub stage (all are C-shaped)	Larvae feed on plant roots in late summer and early spring. Larvae grow to 12.5 mm in length.	Rarely observed, larvae feed on plant roots in summer and early spring. Larvae grow up to 18 mm in length.	Larvae feed on plant roots in late summer and early spring. Larvae grow to 15 mm in length.	Larvae are in soil for three years and feed all through the growing season. Larvae grow to 40 mm in length.
How to ID	Larvae have 2 short rows of stout spines in a v-pattern on the raster and a crescent shaped anal opening.	-	Look for 2 nearly parallel rows of spines on the raster (last body segment) and a y-shaped anal slit	Look for 2 parallel rows of stout spines on the raster (last body segment) and a y-shaped anal slit.

Biology
This insect has one generation per year. Larvae overwinter in the soil within 15 cm of the soil surface. As temperatures rise in spring, they move into the upper layer of the soil to begin feeding on roots of grasses or other hosts. By May, they form a soil cell around themselves and begin pupation. Adults emerge in late June and early July and can remain present in raspberries until early September. The adults mate on plants and often several beetles will be found on the same fruit as they feed. The females dig into the soil to lay their eggs. Adults have a lifespan of 30 to 45 days and each female can lay as many as 50 eggs during that time. Eggs are round and white, and about 1.5 mm in diameter. The eggs hatch after approximately two weeks and the emerging larvae feed on grass roots. Once soil temperatures fall below 10°C, larvae become dormant until spring.

Period of Activity
Adult beetles emerge in late June and early July and can remain present in brambles until early September. Feeding damage is most pronounced in fall-bearing varieties when adult beetle populations peak.

Scouting Notes
Look for feeding damage on leaves in late June and July as well as for the presence of the beetles themselves. Inspect plantings weekly as beetles can fly great distances and may travel from their over-wintering sites to the raspberry field to feed. Male and female beetles may also be lured to traps by Japonilure, which is an artificial lure containing a sex hormone and floral volatiles.

Thresholds
None established.

Management Notes

• Because Japanese beetle grubs feed on grass roots, having grass as a cover for row middles may be detrimental when dealing with heavy beetle infestations.
• Pheromone traps can be used to attract and capture Japanese beetles. However, traps should be placed outside of the raspberry field because many beetles can be lured to the trap but not caught by it. These can cause severe damage to plants near the trap, and could contribute to higher overwintering populations.
• Sanitation is an important aspect in minimizing Japanese beetle populations. Remove overripe, fallen fruit which act as a powerful attractant to the beetles.
• Control white grubs in adjacent lawns or turfgrass using a registered insecticide.
• Moles, skunks and birds are natural enemies of Japanese beetle larvae.