Scentless Seed Bug
Arhyssus spp.
Scentless seed bug adult on sunflower.
Top and underside of scentless seed bug adults.
Arhyssus. spp. adult on sunflower.
Hosts
- Field-grown hemp (primarily for seed)
- Globe mallow
- Mavaceae family
- Weeds in xeric conditions
Description
The head and body of adults are predominantly dull brown with greenish hues. The posterior portion of the wings are clear and the posterior margins of the abdomen are lined with alternating dark and lighter rectangles. Nymphs are smaller, similarly colored, without wings, and rounder in appearance.
Life Cycle
Egg | Larva | Pupa | Adult
- About 2 generations per year.
- Overwinter as adults.
- Adults lay eggs on host plants.
- Bugs migrate from neighboring host plants when they dry out, are sprayed with herbicide, or if they are cut. Migrations of scentless seed bugs into a hemp field could coincide with these events
Damaging Lifestage(s): Nymph, Adult
Damage Symptoms
Adults and nymphs feed with piercing-sucking mouthparts, primarily on seeds. As host plants die or desiccate, aggregations of adults may move to feed on hemp seeds.
Time for Concern
June through harvest (when seeds are present).
When and Where to Scout
- Visually scout plants or use a sweep net in nearby weeds for adults and nymphs starting in early spring.
- Monitor weeds (mallows or other) within the hemp crop for plant bug activity.
- Look for aggregations on individual plants when seeds are present.
Threat Level
Low. In hemp, scentless seed bug feeding will likely have minimal effect on hemp seed production. Large numbers may occur if nearby host plants die or are cut down, forcing migration of the insect.
Occurrence in Utah
Not yet reported as a pest on hemp grown for seed.
Management
- Low numbers do not need to be managed.
- Manage mallow and other weeds in and around the crop.
When to Consider Treatment
Only if large, damaging populations are present. Thresholds have not been developed for hemp.
Look-alikes
Other plant or seed bugs, false chinch bugs, big-eyed bug (beneficial).
Photo Credits (from top to bottom)
- Judy Gallagher, Wikipedia
- Hanna Royals, Museum Collections Heteroptera, USDA APHIS PPQ, Bugwood.org
- Whitney Cranshaw, Colorado State University, Bugwood.org