Blattella asahinai

Mizukubo, 1981

Asian cockroach

Blattella asahinai, the Asian , is a small peridomestic cockroach first described in 1981 from Okinawa, Japan. It is nearly morphologically identical to the (B. germanica) but occupies distinct , preferring outdoor with leaf litter and vegetation. The species is a strong flier attracted to light, contrasting with its -avoidant relative. Since its introduction to Florida in 1986, it has spread throughout the southeastern United States, where it can reach extremely high densities in suitable habitats.

Blattella asahinai by (c) Natasha Wright, Florida Department of Agriculture and Consumer Services, Bugwood.org, some rights reserved (CC BY). Used under a CC-BY license.

Blattella asahinai the Asian cockroach - nymph 06 by Natasha Wright, Florida Department of Agriculture and Consumer Services, Bugwood.org. Used under a CC BY 3.0 license.

Pronunciation

How to pronounce Blattella asahinai: //blæˈtɛlə ˌɑːsəˈhaɪnaɪ//

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Identification

Most reliably distinguished from the () by rather than appearance: B. asahinai flies readily and is attracted to light, while B. germanica rarely flies and avoids light. Wings are longer and narrower than in B. germanica, extending beyond the . Detailed morphological examination reveals differences in the surface of the left , coloration of the right tegmen, wing venation, and setal marginal bristles on the . These characters require magnification for accurate assessment.

Images

Habitat

Predominantly outdoor; favors shaded, mulched, or composted areas with accumulated fresh plant litter. Common in grassy areas, leaf litter, and ground-level vegetation. Strongly associated with cypress, oak, and pine leaf litter mulches; avoids rubber mulch and topsoil. Forms dense in suitable locations. During adverse conditions (cold or dry weather), burrows into leaf litter. Rarely establishes permanent indoor despite attraction to light sources.

Distribution

Native to East Asia (Japan, China). Introduced to United States: first detected in Lakeland, Florida in 1986, believed to have arrived via import of goods from Japan. Established throughout Florida and spreading into Alabama, Georgia, South Carolina, and Texas. Confirmed in Harris County, Texas since 2006. Records from India, Andaman Islands, and Chagos Archipelago.

Seasonality

peaks in late August; activity declines rapidly with onset of cool weather. Most active at dusk. most abundant during summer and spring in Florida.

Diet

. Documented feeding on: human food, pet food, flowers, agricultural crops (lettuce, cabbage, strawberries), and lepidopteran (Helicoverpa zea, Spodoptera exigua) in soybean and cotton crops.

Life Cycle

stage: carried by female until hatching; ~35–40 eggs per ootheca; female produces approximately 4 oothecae lifetime (fewer than B. germanica). approximately 19 days at 25°C. Nymphal development: 6–7 instars typically, requiring 60–70 days for females, slightly less for males. longevity: approximately 50 days for males, 100 days for females. First ootheca produced approximately 13 days after adult . Peak February–May and August–September.

Behavior

Strong, active flier—primary mode of movement, especially when disturbed. Strongly attracted to light and light-colored surfaces; flies toward buildings at dusk, entering through open doors and windows. Predominantly . Forms dense (hordes) of 30,000–250,000 individuals per acre in favorable . Dominates local fauna in preferred outdoor locations.

Ecological Role

Significant of agricultural pest ; in Texas Rio Grande Valley, comprised 53.7% of all predators observed feeding on bollworm (Helicoverpa zea) and beet armyworm (Spodoptera exigua) eggs in soybean crops. May contribute to of lepidopteran pests in agricultural systems.

Human Relevance

Peridomestic nuisance pest; attracted to outdoor lighting and may enter structures but rarely establishes indoor . Can reach extremely high densities in landscaped areas, causing concern to homeowners. Potential allergen source similar to other , though specific allergenicity less studied than B. germanica. effective against often ineffective against Asian cockroach, complicating pest management. Scatter baits developed specifically for this species have proven effective.

Similar Taxa

Blattella germanicaNearly identical ; distinguished by behavioral differences ( capability and light attraction), slightly shorter wings, and preference (indoors vs. outdoors).
Blattella vagaShared and similar size; B. vaga (field ) has different associations and distribution.