Blissus occiduus

Barber, 1918

Western Chinch Bug

, the western chinch bug, is a phloem-feeding true (Hemiptera: Blissidae) that is a significant pest of warm-season turfgrasses, particularly buffalograss and zoysiagrass. The exhibits strong preference hierarchies, with buffalograss being the most preferred host followed by zoysiagrass, though it can survive and reproduce on a broad range of grasses including agronomic crops. Field studies have documented inconsistent control with neonicotinoid , with thiamethoxam showing particularly rapid degradation in buffalograss tissues compared to imidacloprid and clothianidin.

Blissus occiduus by (c) Chris Ratzlaff, some rights reserved (CC BY), uploaded by Chris Ratzlaff. Used under a CC-BY license.

Pronunciation

How to pronounce Blissus occiduus: /ˈblɪsəs ɔkˈsɪdjuːs/

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Identification

are small, approximately 4-5 mm in length, with the characteristic chinch bug body plan: oval, somewhat flattened, with a dark body and contrasting wing markings. The forewings are primarily white with a distinct black triangular spot at the middle of the outer margin. Nymphs lack wings and progress from yellowish to reddish with a pale band across the , eventually becoming dark with a conspicuous white spot between the wing pads. Distinguished from the hairy chinch bug (Blissus leucopterus hirtus) and common chinch bug () by geographic distribution and associations; B. occiduus is the primary chinch bug pest in western North America and shows particularly strong association with buffalograss, which is not a preferred host of eastern chinch bug .

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Habitat

Turfgrass systems, particularly buffalograss and zoysiagrass lawns and research plots; agricultural fields with grass crops; weedy grassland areas. Associated with managed and unmanaged grassland where warm-season grasses predominate. In field studies, concentrated in buffalograss leaf tissues where distribution and degradation patterns have been characterized.

Distribution

United States (California, Colorado, Kansas, Montana, Nebraska, New Mexico) and Canada (Alberta, British Columbia, Manitoba, Saskatchewan); also reported from Central America. Western Nearctic distribution, excluding Beringia.

Diet

Phloem-feeding on grasses (Poaceae). Strongly prefers warm-season turfgrasses, with buffalograss (Bouteloua dactyloides) and zoysiagrass (Zoysia japonica) as primary . Will feed and reproduce on diverse grass hosts including bermudagrass, St. Augustinegrass, centipedegrass, tall fescue, ryegrass, Kentucky bluegrass, creeping bentgrass, sorghum, corn, wheat, rice, barley, oats, and various weed grasses including crabgrass, foxtail, goosegrass, fall panicum, barnyardgrass, and johnsongrass. Host suitability varies significantly, with some hosts supporting high survival and while others result in high nymphal mortality.

Host Associations

Bouteloua dactyloides (buffalograss) - primary - most preferred, supports highest survival and
Zoysia japonica (zoysiagrass) - primary - second most preferred
Cynodon dactylon (bermudagrass) - - supports development
Stenotaphrum secundatum (St. Augustinegrass) -
Eremochloa ophiuroides (centipedegrass) -
Festuca arundinacea (tall fescue) - poor - high nymphal mortality
Lolium perenne (perennial ryegrass) -
Poa pratensis (Kentucky bluegrass) - poor
Agrostis stolonifera (creeping bentgrass) -
Sorghum bicolor (sorghum) - agricultural
Zea mays (corn) - agricultural
Triticum aestivum (wheat) - agricultural
Oryza sativa (rice) - agricultural
Hordeum vulgare (barley) - agricultural
Avena sativa (oats) - agricultural
Secale cereale (rye) - agricultural
Digitaria sanguinalis (large crabgrass) - weed
Digitaria ischaemum (smooth crabgrass) - weed
Setaria spp. (foxtail species) - weed
Eleusine indica (goosegrass) - weed
Panicum dichotomiflorum (fall panicum) - weed
Echinochloa crus-galli (barnyardgrass) - weed
Sorghum halepense (johnsongrass) - weed

Behavior

Exhibits gradual relocation : if initial host selected is suboptimal, individuals move to more preferred hosts over 72 hours. Initial host selection appears based on morphological characteristics and plant architecture, particularly stoloniferous growth habit providing cover. In choice studies, over 50% selected buffalograss or zoysiagrass within 8 hours, increasing to over 70% by 24 hours. Can colonize and reproduce on multiple hosts but maintains clear preference hierarchy.

Ecological Role

Pest of turfgrass and agricultural systems; damages preferred through phloem feeding. Potential to build high on alternate hosts while remaining undetected, then move to preferred hosts or adjacent crops. influenced by host plant availability and quality.

Human Relevance

Significant pest of buffalograss and zoysiagrass turf, causing damage through feeding that can result in lawn damage and turf loss. Subject to management with neonicotinoid , though field efficacy is inconsistent. Thiamethoxam shows particularly poor residual activity due to rapid degradation in buffalograss tissues (700-fold decline over 28 days versus 60-70 fold for imidacloprid and clothianidin). Imidacloprid achieves higher concentrations in leaf tissue and may provide more consistent control. Management complicated by preference and ability to survive on diverse grass hosts.

Similar Taxa

Blissus leucopterus hirtus (hairy chinch bug)Similar size, coloration, and wing pattern with black triangular spot on white forewings; distinguished by geographic distribution (eastern North America) and preferences, particularly strong association with cool-season turfgrasses rather than buffalograss
Blissus leucopterus leucopterus (common chinch bug)Similar ; distinguished by distribution (eastern and central North America) and lack of strong preference for buffalograss
Nysius raphanus (false chinch bug)Similar and grass-feeding habit; distinguished by dull yellowish-gray coloration, transparent wing tips extending beyond , and lack of distinct black wing markings