A discussion of the range expansion of the Turkestan cockroach.
The Turkestan cockroach, Blatta lateralis (Walker) (Dictyoptera: Blattidae), probably received its common name from the fact that it was collected in the Asian province of Turkestan. It is thought to be native to Egypt, Libya, Sudan, Saudi Arabia, Israel, Jordan, Iraq, Iran, Pakistan, India, the Soviet Central Asia, Kashmir and Afghanistan.
Blatta lateralis was introduced into the United States probably in household goods of military personnel and military material brought back from the Middle East. It was first reported in the United States in May 1978 from Sharpe Army Depot, a military facility in Lathrop, Calif. (Caruba 1979, Gurney 1978, Spencer et al. 1979). However, since 2000, nothing further appeared in the literature regarding the Turkestan cockroach in the United States.
The purpose of this article is to report new distributional records for B. lateralis, to contribute additional ecological information on this exotic species and to outline for the first time, an IPM program for this roach in school environments.
ADDITIONAL DISTRIBUTION. In August 2001, a Los Angeles Unified School District (LAUSD) IPM technician brought in specimens of cockroaches that were caught on sticky traps for identification purposes. The roaches on the traps were identified as Turkestan cockroaches. This is the first report of an established infestation of B. lateralis in Los Angeles County. Since that time, other Turkestan cockroaches have been found. These infestation sites are in the same ZIP code and within several blocks of each other. This indicates a well-entrenched, extensive infestation of B. lateralis in this area, as well as infestations in two different cities.
Benson and Zungoli (1997), referring to the Turkestan cockroach, stated that: "In the first decade after it was detected, this cockroach did not increase its range appreciably." Gulmahamad (1993) stated that: "It is my belief that other infestations of this cockroach currently exist in other areas of Southern California." I am convinced that other undetected infestations of the Turkestan cockroach currently exist in Southern California. This is based on the fact that pest control technicians readily misidentify the male of the Turkestan cockroach as an American cockroach and the female as an Oriental cockroach. From the new distributional records presented here, it is clear that the Turkestan cockroach is increasing its range in California and it is becoming a peridomestic cockroach pest in infested areas.
A SCHOOL INFESTATION. The discovery of a heavy infestation of the Turkestan cockroach at the Cantara Street School afforded an opportunity to add to our knowledge of this exotic species. As early as February 2003, Turkestan cockroaches were being captured on indoor monitoring sticky traps at this location. By May 2003, significant numbers of B. lateralis were being caught on sticky traps deployed indoors in classrooms, offices, faculty lounge, storage rooms, etc. Occupants of the affected structures began complaining about roaches saturating the sticky traps and they were requesting that the monitors be replaced on a more frequent basis. Examination of sticky traps that were deployed indoors in June 2003 revealed that both Oriental and Turkestan cockroaches were being caught at this location with B. lateralis being the dominant species.
Based on surveys of accessible in-ground boxes on the school grounds and counts of roaches flushed out of cracks and crevices in hardscapes, cold joints, expansion joints and other harborages on the property, it is estimated that the populations of peridomestic cockroaches on this campus at this time is approximately 75% Turkestan and 25% Oriental cockroaches.
The most common harborage site for the Turkestan cockroach on the grounds of this school is in-ground boxes (see Figure 1 above). About 77 in-ground boxes were counted on this school property. These boxes were marked as water meter, electric, sewer, gas shut-off valve, irrigation control valve, etc.
The other significant exterior harborage for B. lateralis on this campus were cracks in the exterior hardscapes, cold joints, expansion joints and various void areas under hardscapes. It is important to point out here that San Fernando Valley, Calif., where the above mentioned schools are located, was hit by two significant earthquakes: one in 1974 and one in 1991. These earthquakes created ubiquitous fissures in hardscapes throughout the valley and these cracks are now serving as ideal, protected harborages for both the Oriental as well as the Turkestan cockroach in this geographic area.
It is my belief that abundant earthquake cracks in hardscapes are significant contributors to the high populations of Oriental and other peridomestic cockroaches in the San Fernando Valley. The exterior of the Cantara school is, for the most part, covered by hardscapes with the exception of some dry tree wells and a few areas at the front of the school and along the streets which contain some vegetation ground cover. Because of this situation, good exterior harborages for both the Turkestan and Oriental cockroaches are limited. At this site, in-ground boxes which harbor Oriental roaches only contained Oriental roaches and those that harbor Turkestan cockroaches only had Turkestan roaches in them. Occasionally a few male Turkestan roaches were observed in in-ground boxes that contained Oriental roaches only. Males of some species of peridomestic cockroaches are known to range farther afield than females.
CONTROL. As of this writing, I am not aware of any insecticide label in the United States that lists the Turkestan cockroach as a target pest. Nagata et al. stated that any pest management program which controls peridomestic cockroaches should control the Turkestan roach. In the United States, it is legal to use site-specific insecticides to control a pest that is not on the label as long as the site is on the label and the label does not specifically prohibit such use.
Our approach to controlling the Turkestan cockroach at the Cantara location was to locate and treat all of the outdoor harborages. This entailed treating all outdoor, in-ground boxes and cracks, crevices, cold joints, expansion joints and other exterior harborages. This represents precision material placement and a focused and targeted chemical application.
This work was scheduled for completion on a day when the school was closed. Hand dusters were used to apply a 0.05% deltamethrin dust to exterior cockroach harborages. This material was chosen because it has flushing action, a relatively quick knockdown and kill, long residual activity, effectiveness in moist environments and small amounts (grams) were needed to achieve desired results. Using very small amounts of a low percentage, high efficiency product and placing it in areas that are inaccessible to students, faculty, staff and non-target organisms are important considerations when conducting pest management work in school environments.
Several lessons were learned from treating the exterior harborages as described previously. Deltamethrin dust, applied in in-ground boxes, is highly irritable to Oriental and Turkestan cockroaches. Almost immediately after dust was applied inside an in-ground box, the roaches would start exiting the box in large numbers. Oriental cockroaches streaming out of a treated in-ground box was described by one LAUSD IPM technician as "flowing black water."
My initial reaction to this mass exodus of cockroaches was to seal all of the exits with tape so that the roaches would die in the boxes. Several veteran LAUSD technicians cautioned against doing that. It seems that over the years, LAUSD staff, faculty, custodian and maintenance workers, have come to judge the efficacy of an outdoor peridomestic cockroach control program based on how many dead roaches were found on the hardscapes after the work was completed (see Figure 2 on page 78). School plant managers, on several occasions, have expressed dissatisfaction with peridomestic cockroach control program when they do not see large numbers of dead roaches after a treatment.
The second lesson learned was cockroaches that exited treated in-ground boxes would disperse before they eventually die. This resulted in roaches entering buildings, including classrooms, particularly under doors that did not have door sweeps. They would eventually die on the floors out in the open. If these large, conspicuous roaches are not removed before occupants returned, one can expect complaints, consternation, disgust and alarm from users of the affected structures.
In addition to dusting outdoor harborages to bring about a quick reduction of the cockroach population, a hydramethylnon granular bait, labeled for controlling peri-domestic cockroaches, was applied in small amounts as spot treatments to certain high profile cockroach harborage areas. This was done to obtain control of cockroaches that were harboring in various vegetation ground covers.
The Turkestan cockroach infestations in the drop ceiling areas of two prefabricated buildings were treated at the same time the exterior treatment was rendered with an orthoboric acid granular bait that was placed in bait trays and deployed on the ceiling panels in several areas. This bait was used because it was reported to be resistant to heat. Three weeks after this treatment, the treated areas were inspected. Visual counts reveal that the cockroach populations appeared to be the same as they were prior to the treatment and no dead cockroaches were visible on top of the ceiling panels. At this point a cockroach gel bait was deployed in bait trays at several locations on top of the ceiling panels.
One week later the area was inspected to assess and evaluate the efficacy of this bait. It was discovered that all of the available gel baits were consumed and the cockroaches even ate into the cardboard below each bait placement in a desperate attempt to get at bait that absorbed into the bait trays. Dead cockroaches were present everywhere. However, monitoring traps placed on the drop ceiling panels were still catching cockroaches. This indicated that the cockroach populations in this area were larger than we thought and that enough bait was not deployed to eliminate the entire cockroach population. Adequate amounts of gel bait were subsequently placed in bait trays at strategic locations on top of the drop ceiling panels and this second treatment brought about the desired results. The presence of many dead cockroaches and their fecal pellets on the ceiling panels became a concern from an allergen point of view and this required the use of vacuum devices with high efficiency particulate air filters to remove the cockroaches and their accompanying allergens from this area.
Turkestan cockroach stragglers that were already present inside various structures at the time of the exterior treatment were removed by deploying an adequate number of sticky traps in strategic locations. Since B. lateralis is a slow-reproducing cockroach that travels about at night scavenging at floor level, it was not difficult to trap out the indoor individuals using sticky traps with good attractants. Monitoring traps placed inside affected buildings one week after the exterior treatment told us that we had crashed the population as only a few specimens were being caught indoors.
With an eye towards the long-term prevention of this problem and in an attempt to further limit the use of chemicals on this school facility in the future, a request was made to install door sweeps on doors of those buildings that had a history of peridomestic cockroach invasions. It must be pointed out here that door sweeps by themselves are not a solution to this domiciliary cockroach problem. Custodians working the night shift at this school reported that it is difficult to walk the grounds of this school on hot summer nights without stepping on cockroaches. When peridomestic cockroach populations reach such high densities outdoors, control intervention has to be taken to mitigate the problem.
CONCLUSION. The IPM program outlined here for controlling the Turkestan cockroach, a species about which little is known in the U.S., was based entirely on specific and detailed knowledge about the biology, behavior, foraging ecology and preferred harborage sites of this species. By possessing this knowledge, we were able to rectify this pest situation without applying any materials inside the living space of any of the school buildings. Focused and targeted applications of small amounts of materials (grams) were made directly to preferred cockroach harborages where they did the most good and where they were essentially inaccessible to people, pets and other non-target organisms.
IPM is a knowledge-based process. The more you know about a target pest, the easier it will be to manage it even in sensitive environments such as schools. In cases where one is dealing with exotic pests, of which little is known in the United States, keen and perceptive field observations must be made on which intelligent decisions can be based. Also, knowing what is available to you in the marketplace with respect to materials, supplies, equipment, etc., enables an informed person to make smart choices regarding the selection of minimum risk materials to obtain the desired results while concurrently minimizing undesirable effects on the environment and non-target organisms. This program was successful largely because it was based on meticulous real-world field observations and it was executed by knowledgeable people.
The author is a board certified entomologist and an urban and structural entomologist and IPM coordinator, Los Angeles Unified School District.