A retired UC Davis professor recently reported spotting an unusual cockroach emerging from his shower drain at his home in Davis, California. The insect was identified as a male Turkestan cockroach (Blatta lateralis), a species that has been present in the United States since 1978.
The Turkestan cockroach, also known by other scientific names such as Shelfordella lateralis and Periplaneta lateralis, was first detected near the Sharpe Army Depot in Lathrop, San Joaquin County. Scientists believe it arrived with military equipment returning from Central Asia.
Lynn Kimsey, UC Davis Distinguished Professor Emeritus and former director of the Bohart Museum of Entomology, commented on the presence of these insects: “Yes, Turkestan roaches have been around for a few years. People usually don’t notice them because they’re largely outdoor roaches. But they are all over the sidewalks in downtown Davis at night. Right now, there are eight exotic roaches in California, and I just got sent a photo of another that I can’t recognize. Yay, international travel…:”
Kimsey explained further about exotic cockroaches found in California: “There are currently eight species of exotic cockroaches in California. Three of these, the American cockroach, brown-banded cockroach and German cockroach are indoor pests. These species tend to be scavengers. The remaining species are outdoor pests that will occasionally come indoors but do not normally reproduce indoors. These outdoor roaches tend to be more detritivores and herbivores.”
The list includes:
– Turkestan Cockroach (Shelfordella lateralis)
– Oriental Cockroach (Blatta orientalis)
– American Cockroach (Periplaneta americana)
– Smoky Brown Cockroach (Periplaneta fuliginosa)
– German Cockroach (Blattella germanica)
– Garden Cockroach (Blattella vaga)
– Brown-banded Cockroach (Supella longipalpa)
– Tiny Cockroach (Luridiblatta trivittata)
According to the UC Statewide Integrated Pest Management Program website, the Turkestan cockroach is typically found outdoors in locations like water meter boxes, cracks between concrete blocks, compost piles, leaf litter, potted plants, and sewer systems. This species is sometimes sold online as food for insect-eating pets.
The program describes how female Turkestan cockroaches can be distinguished from oriental cockroaches by cream-colored markings behind their heads and around their wings; males look similar to American cockroaches but are smaller with yellowish-beige wings featuring cream-colored stripes along the edges.
UC IPM notes: “The biology of the Turkestan cockroach is similar to that of the oriental cockroach, though Turkestan cockroach females reach maturity faster and produce more eggs during their lifetimes than oriental cockroach females.” In recent years, this species has displaced oriental cockroaches across southern California, the Central Valley and other warm areas.
Despite some confusion about its novelty locally, fossil evidence indicates that ancestors of modern-day roaches have existed for over 300 million years—predating dinosaurs.
For those interested in seeing live specimens or learning more about local insect fauna, information sheets are available on the Bohart Museum’s website at https://bohart.ucdavis.edu/insect-info-sheets.
Each year during UC Davis Picnic Day events held at Briggs Hall—scheduled next for Saturday April 18—the Department of Entomology and Nematology hosts “Roach Races” featuring American cockroaches.