| Maple Bugs / Box Elder Bugs | Root Weevils (Strawberry Root Weevils)
Each year, whether summer or fall, a number of insects will gather together and make attempts to enter buildings to shelter and/or overwinter. Most are not plant pests, and are merely nuisance insects that invade our residences. This article is meant to provide a bit more information on a couple of invaders that you might encounter.
Maple Bugs / Box Elder Bugs
Causal Agent: Boisea trivittata
Host plants: Various species of maple (Acer) and ash (Fraxinus); No agricultural crops
Description:
- Adults are narrow, 14mm (1/2 inch) long insects, black/dark grey in colour, with red along the edges of their wings, and three distinctive stripes on their thorax (upper back/shoulders).
- Stripes form a subtle X on the back when wings are folded flat (similar insects have a more distinct X)
- Nymphs (immature stages) are bright red, with black wing buds
- Nuisance pest
- Stain surfaces when squished
- Crushed bugs emit a foul odor
- Poop can stain fabrics
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Adult and various nymphal stages of Box Elder Bug | |
Photo by: William M. Ciesla, Forest Health Management International, Bugwood.org | |
Life Cycle:
- Adults emerge in the spring to lay eggs on the leaves and bark of host trees
- Nymphs feed on seeds, foliage, twigs and fruit
- Nymphs progress through several developmental stages until they become adults and begin reproducing immediately
- Feeding on host trees does little damage
- 2nd generation of adults will overwinter
- Large numbers of nymphs and adults will be observed on the trunks of trees in early fall, just prior to migration
- Insects seek a protected location to overwinter
- Locations must be warm enough to be above freezing while they hibernate, but not so warm that they will expand all of their energy reserves and die
- 4-10°C (40-50°F) is the preferred temperature range
- Only adults have sufficient energy to survive the winter; the remainder of the insects (nymphs) will die
Management:
- Block entrance points into buildings by caulking gaps and ensuring screens are intact
- Vacuum up rogue invaders to avoid stains or odors
- Spray groupings of mature/immature insects prior to migration with a mixture of water and dish soap (3-4% solution)
- Contact with soapy solution will suffocate insects – insects not contacted with solution are unaffected
- Removing host trees may remove breeding sites
Root Weevils (Strawberry root weevil)
Causal Agent: Otiorhynchus ovatus
Host plants: strawberries
Description:
- Adults are shiny, dark brown-black beetles, about ¼ inch in length, with blunt snouts and antennae that have elbows
- Root weevils will drop to the ground when disturbed, do not fly and are nocturnal, emerging only at night to climb plants
- Larvae are pale and legless
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Strawberry Root Weevil adult | |
Photo by: Whitney Cranshaw, Colorado State University, Bugwood.org | |
Life Cycle:
- Root weevils overwinter as nearly fully grown larvae
- Pupation is completed in the soil, with adults emerging in early summer
- Eggs are laid near plant crowns
- Larvae feed on host plant roots, whereas adults feed on leaves (resulting in leaf margin notching symptoms)
- Adults often migrate into homes in late spring and late summer, perhaps to avoid hot, dry conditions
Management (around structures):
- Block entrance points into structures
- Vacuum up beetles found crawling around residences
- Insecticidal treatments are generally unnecessary and/or ineffective – may be applied around the exterior of a structure
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