Cockroaches are one of the most common of all insects and have been for more than 300 million years, as evidenced by fossil remains. All cockroaches are nocturnal, making it easy for populations to build to huge numbers before their presence is realized. There are many other common species of cockroaches, including the brown-banded and oriental roaches—and the recently identified Asian cockroach (Blattella asahinai).
Read on to learn how to control this pest in your home.
Identifying Asian Cockroaches
Asian cockroaches are often mistaken for their similar-looking counterpart, the German roach. Both species of cockroach adults are about 13 to 16 mm long, light brown, and have two visible parallel lines behind their heads on the pronotum.
Because the Asian roach feeds primarily on plant material, it does not pose quite the same danger of disease transmission as other species, especially the German roach, which is primarily a garbage feeder. But like other cockroaches, the Asian roach can cause asthma issues for people allergic to the insects. Moreover, this large insect flies about indoors at night, making it a decided nuisance.
Signs You May Be Seeing Asian Cockroaches
These roaches are a common pest in the Southeastern United States, first making their appearance in the 1980s. Though they are mostly an outdoor pest, you could spot them inside or around your home, especially at night. The roaches become active at dusk and fly towards light sources, much like moths, making them attracted to TV screens and other lamps.
3 Ways to Get Rid of Asian Cockroaches
In general, cockroaches in the home are controlled through a combination of sanitation, traps, baits, and chemicals. However, because every cockroach species varies, so too will its control. For example, although a common control method for most species is to apply a residual spray around the perimeter of a home, this method is largely useless for flying Asian cockroaches, which generally just fly into a home through open windows and throughout wooded areas. Nor does indoor baiting do much to control Asian roaches, since they are not colonizing indoors but rather are opportunists that fly in whenever the opportunity presents itself.
But there are ways to control the Asian cockroach; some methods are common to how all other species are controlled, while others are unique to this particular species.
Unlike other species of roaches, Asian cockroaches don't nest indoors, and when they do get indoors, they are drawn to light sources, such as lamps and television sets. It is quite possible to crush or net the insects when you find them, though in some regions this can be an ongoing activity at certain times of the year. Asian roaches are most active in the spring and early summer, and homeowners in some regions may find themselves catching or killing five or 10 bugs each evening—especially if the home is not tightly sealed against insect intrusion.
Use Pellet Baits
If infestations are serious, the most effective means of control is to use pellet-type outdoor baits spread around the garden in likely nesting areas—mulch piles, etc. Make sure, however, to use products designed for outdoor use, as most indoor baits are not very effective when exposed to the weather. Pellet-type baits are much more effective than gel-type baits for outdoor use.
Spray With Indoor Pesticide
A variety of traditional pesticides will kill Asian roaches if they are sprayed. This can be a difficult challenge, however, since the bugs must be hit directly with the spray, and they are very adept at flying away from threats. Pesticides based on pyrethrin compounds—derived from chrysanthemum flowers—are among the safest, least toxic of contact sprays.
What Causes Flying Asian Cockroaches?
Asian cockroaches are most likely to be found in damp outdoor locations where there is thick mulch or lots of plant litter. Plant material is the primary food of these insects, but like all cockroaches, the Asian roach is a diverse feeder that is also happy to feast on garbage and food scraps if it happens to find them.
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How to Prevent Flying Asian Cockroaches
Asian cockroaches generally find their way indoors through open windows and doors, through insect screens that are torn, or through gaps and cracks in walls and foundations. Make sure that all windows and doors are fitted with screens that are in good condition, and coach your family members to limit their in-and-out habits, especially around dusk in late spring and summer when the insects are most active. Porch lights tend to lure outdoor roaches, so keep these turned off as much as possible; or replace standard bulbs with sodium vapor or yellow incandescent bulbs, which are less likely to lure the bugs.
These insects prefer to nest in damp mulch and plant litter, so keeping your garden and lawn relatively clean will reduce outdoor populations, which will also reduce the number that flies into your home.
Flying Asian Cockroaches vs. German Cockroaches
Of the approximately 50 cockroach species that occur in the U.S., the German and American cockroaches are two of the most common species that infest homes, restaurants, hotels, and other establishments. Asian cockroaches are often mistaken for German cockroaches since they are nearly identical in appearance. Some experts suggest that they may be varieties of the same species since they have been known to cross-breed and produce hybrid offspring.
However, there are key differences between the two types, especially in their behavior. The Asian cockroach is primarily an outdoor insect that feeds mostly on plant material and honeydew excretions from aphids. The German cockroach is an indoor dweller that feeds primarily on foods. And while the German cockroach rarely uses its wings, preferring instead to scurry about on its legs, an Asian cockroach is an avid flyer and is quite agile in the air. An Asian cockroach that is found indoors often gets there by accident, flying in through an open door or window.
While you might think that this makes the Asian cockroach a trivial indoor problem, they can be very populous in some regions, with numbers ranging from 30,000 to 250,000 per acre. This skilled flyer can easily invade a home through open doors and windows, making it a very annoying pest. And once it does get into the house, it is quite happy to feast on whatever food it finds there—just like a German roach.
For a home located in a region where Asian cockroaches are common, it may sometimes seem like this species is a much bigger problem than other cockroaches. This is somewhat illusory, however, because Asian cockroaches don't hide like other species—they readily fly around the house when lights or televisions are glowing in the evening.
First found in the U.S. in 1986 in the Lakeland, Florida, area, the Asian cockroach has become a significant pest in the areas it infests, primarily the southeastern states. Although similar in looks and size to the German cockroach, the Asian cockroach has slightly different behavioral habits that change how you approach control.
|Asian Cockroach||German Cockroach|
|Scientific Name||Blattella asahinai||Blattella germanica|
|Size||About 5/8 inch long||1/2 to 5/8 inch long|
|Color||Light brown||Medium to dark brown|
|Wings||Wings are long and narrow, overhanging the body||Wings are present but kept tucked against the back|
Do Asian cockroaches bite?
Though bites are quite rare, Asian cockroaches have biting jaws that can pierce skin if the insect is handled. They do not, however, seek to bite humans or other animals, as they are not blood feeders.
Do Asian cockroaches carry disease?
Like other roaches, the Asian cockroach can transmit microorganisms as it moves about. Bacteria from outdoor animal feces, for example, can be carried indoors when the insects fly in.
Do Asian cockroaches damage garden plants?
While Asian cockroaches have been observed eating lettuce, cabbage, strawberries, and some other plants, they are not considered serious pests for gardeners. Except for the fact that outdoor Asian roaches all too often fly their way indoors, there is no reason to worry about Asian roaches in the garden.
Are Asian cockroaches beneficial?
There is some evidence that Asian cockroaches are predators of certain plant-damaging pests, such as bollworms, that affect commercial crops. The evidence is not so strong, however, to warrant encouraging Asian roaches as a biological control.
Do, Dan C. et al. "Cockroach Allergen Exposure And Risk Of Asthma." National Institutes of Health.
"Asian Cockroach - Blattella Asahinai Mizukubo." University of Florida Extension.
Hopkins, John D. "Cockroach Identification And Management For The Homeowner." University of Arkansas Division Of Agriculture Research & Extension.
"Cockroaches: Unhygienic Scavengers In Human Settlements." World Health Organization.