Ministry of Agriculture

New Insect Pest Introductions to B.C.

In 2001, four new insect pests of ornamental plants were confirmed to occur in British Columbia. This factsheet provides information on the biology, distribution and management of these pests.

Viburnum Leaf Beetle
(Pyrrhalta viburni)

Biology and Symptoms:
Both the adult and larval (Figure 1) stages feed exclusively on Viburnum species. European highbush cranberry or Snowball tree (Viburnum opulus) is a preferred host. Heavy infestations can defoliate shrubs, causing die-back and death after repeated infestations. Highly susceptible species can be killed in 2-3 years. Larvae are present in early spring, followed by adults in early summer, after a short pupation period.  In summer, adults lay overwintering eggs inserted into one- or two-year-old branches.

larva Figure 1. Viburnum Leaf Beetle Larva.
Photo courtesy OMAFRA.
skeletonized leaves Figure 2. Viburnum Leaf Beetle.
Larva and adult feeding skeletonizes leaves.
egg-laying sites Figure 3. Viburnum Leaf Beetle.
Overwintering egg-laying sites.

Known Distribution:
Vancouver Island and the Fraser Valley

Management:
Prune out and destroy twigs infested with eggs (Fig. 3). Control larvae and adults with registered insecticides.

European Chafer
(Rhizotrogus majalis)

This is a very serious pest of turf, horticulture, and field crops in Ontario and in the north eastern United States.

Biology and Symptoms:

The adult is a large (12 mm long), brown, leaf-feeding beetle which looks similar to the June beetle. Beetles can be seen gathering together in groups in trees in June-July. Adults mate and lay eggs in the soil in July. Larvae hatch and begin feeding in July, and remain in the soil until pupation the following spring. The larvae or grubs (Fig. 5) feed mainly on the roots of grasses, and are most damaging in the fall and spring when they grow to 2.5 cm before pupating. There is one generation a year. Skunks and birds damage turf when searching for grubs (Fig. 4).

dead turf Figure 4. European Chafer.
Wilted or dead turf that may be pulled up by skunks or other animals.
larvae Figure 5. European Chafer.
Larvae (white grubs).

Known Distribution:
Initial detection was in New Westminster in 2001, and has expanded to Vancouver, Burnaby and Coquitlam. European Chafer has recently been confirmed in East Richmond (2010) and North Delta (2007).

Management:
Keep turf healthy with adequate fertilizer and water. Mow at a height of 6-9 cm (2.5-3 inches). Beneficial nematodes and insecticides are available for control of larvae, and are best applied in summer when the new larvae are beginning to hatch. Nematode application must be followed up with adequate irrigation. Insecticides also require adequate water at application. Consult product labels and professional help for best results. Do not remove soil from infested areas, as it may spread European Chafer to new areas.

Hemerocallis Gall Midge
(Contarinia quinquenotata)

Biology and Symptoms:
The adult is a small, seldom seen fly that lays its eggs in daylily blooms in spring. The maggots feed on unopened flower buds and cause them to become distorted and unable to open. Infested buds will contain numerous white maggots that are around 3 mm in length (Fig. 7). The larvae will grow within the bud, then drop to the ground and pupate for the winter. There is one generation per year. Early flowering varieties are at most risk of infestation. Some varieties are more attractive to the gall midge than others. This pest has the potential to become a serious problem for daylily producers and is commonly found in landscape plantings of daylilies.

infested buds Figure 6. Hemerocallis Gall Midge.
Normal bud above; two infested and swollen buds below.
Photo courtesy Jay Rowland c/o Pam Erikson.
infested bud with maggot Figure 7. Hemerocallis Gall Midge.
Infested bud with maggot indicated by arrow (maggot magnified in top right inset).
Photo courtesy Jay Rowland c/o Pam Erikson.

Known Distribution:
In British Columbia: Lower Mainland, Bowen Island, Vancouver Island. The gall midge occurs commonly in Europe.

Management:

  • Starting when the first buds occur, monitor for distorted buds.  Remove and destroy distorted buds by freezing for 48 hours or burning.  Do not compost.
  • There are no registered chemical control products.  Research indicates that systemic insecticides are effective.
  • The planting of an early yellow daylily trap crop has been found to reduce the population in Southern England, and can be used to protect other varieties.

Andromeda Lacebug
(Stephanitis takeyai)

Biology and Symptoms:
Nymphs and adults (Fig. 9) feed on the undersurface of Pieris japonica leaves, and also attack some rhododendrons and azaleas. Upper surfaces of leaves develop a yellow-speckled or mottled appearance (Fig. 8). Damage can be severe in dryer areas. Insects can be found on the under-surface of leaves, where they feed and hide.  Small black spots of fecal material are good indicators of lacebug presence.  This species overwinters as eggs in plant foliage.  There are 2-3 generations per year. Plant health appears largely unaffected by feeding damage, however this cosmetic damage persists throughout the season.

yellow-speckled damage on foliage Figure 8. Andromeda Lacebug.
Yellow-speckled damage on foliage.
adult lacebug Figure 9. Andromeda Lacebug.
Adult.

Known Distribution:
Fraser Valley, Vancouver Island.

Management:
Wash off pests with water spray. Some insecticides are registered for lacebug control.  The best time to spray is when nymphs are present, as determined by inspecting the underside of leaves.

Ministry of Agriculture
1767 Angus Campbell Road
Abbotsford BC V3G 2M3
Telephone: 604 556-3001

Updated April, 2010