common name: Asian cockroach
scientific name: Blattella asahinai Mizukubo (Insecta: Blattodea: Blattellidae)

Introduction - Distribution and Habits - Description - Life Cycle - Management - Selected References

Introduction

 The Asian cockroach was identified as a newly introduced species to the United States in 1986 when a professional pest control operator collected these insects in Lakeland, Florida. He referred to them as German cockroaches, Blattella germanica (L.), but noted that their behavior was unlike any other German cockroaches that he had previously encountered. Upon further investigation the cockroaches were found to be B. asahinai, Asian cockroaches.

adult female

Distribution and Habits

The Asian cockroach was first described in 1981 from insects collected on Okinawa Island, Japan. It is most likely that B. asahinai was introduced into the United States through imports from Japan. Since the first identification of B. asahinai in Lakeland (Polk County), it has spread through much of Florida, and is reported in Alabama, Georgia, South Carolina and Texas.

The primary habitat of the Asian cockroach is outdoors in shaded mulched or composted areas, such as landscaping and gardens, where fresh plant litter accumulates. Populations of 30,000 to 250,000 insects per acre have been reported. Members of this species are strong fliers, unlike their close relative, the German cockroach. They may invade structures but indoor infestations are rare occurrences. They become active at sundown and are attracted to light-colored surfaces and brightly lit areas. Adults will take flight during the day if disturbed. The presence of this pest is obvious since their peak activity period coincides with our leisure time.

In 2008, the USDA published reports that the Asian cockroach might also have a possible beneficial role, as an egg predator, in controlling lepidopteran pests of annual crops (USDA 2008). However, as it is primarily a pest, there are no plans to distribute it as a biological control.

Description

Asian cockroaches are almost identical to German cockroaches. Chemical analysis by gas chromatography will confirm the species. However, there are also slight morphological differences between B. asahinai and B. germanica. Asian cockroach adults have longer and narrower wings than those of German cockroaches.

wing lengths

There are also differences between the species in the shape of the male tergal glands. Asian cockroach females produce smaller egg capsules and nymphs are smaller than that of German cockroaches. Asian cockroach first instars have 23 antennal segments while German cockroach first instars have 24 to 25. Finally, margins of the abdomen and spots along the abdominal midsection of B. asahinai late instars appear white, whereas those areas are lightly pigmented in B. germanica.

ventral view of egg capsules

dorsal view of egg capsules

early instars

late instars

pronotol stripes

Life Cycle

Female Asian cockroaches have a lifetime reproductive potential for producing approximately four egg capsules (oothecae), each averaging 37 eggs. Immature nymphs take approximately 67 days to reach adulthood. Adult females then live an average of 104 days and adult males live an average of 49 days. Adult females produce their first egg capsule 13 days after adult eclosion, and can drop another 20 days later. Adults are abundant February through May and again August through September. Nymphs predominate May through August.

egg case

Management

Control of Asian cockroaches is difficult due to their mobility and abundance of population sites. Traditional treatments using residual sprays inside and around the perimeter of a structure are ineffective due to numerous infestations in mulched and wooded areas. Plus, adults enter homes through windows and doorways, avoiding areas typically treated for control of German cockroaches. Sodium vapor lamps for security lighting and yellow incandescent bulbs for porch lighting are both less attractive to adults and would thereby reduce attraction of adult insects to lighting near buildings. Although Asian cockroaches are susceptible to all pesticides, toxic pelletized baits scattered outdoors have provided the most reliable control.

Insect Management Guide for cockroaches
Least Toxic Methods of Cockroach Control

Selected References

Author: Dina L. Richman, University of Florida
Photographs: Dina L. Richman and R.W. Baldwin, University of Florida
Project Coordinator: Thomas R. Fasulo, University of Florida
Publication Number: EENY-120
Publication Date: January 2000. Latest revision: August 2008.
Copyright 2000-2008 University of Florida

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