Beware of the spider

Redback spiders and black spiders are basically non-aggressive but have poison and are designated as specific aliens based on the Alien Biology Act. As a result of being carried on cargo, containers, building materials, automobiles, etc., it is thought that the population has expanded, and it has been confirmed in 45 prefectures in Japan (as of July 2020).
In Yokohama City, a spider spider was discovered in 1995, and has been confirmed since then. The redback spider was also found in 2015, 28, 2019, 2020 and 2021.

・The whole is glossy black, the red pattern that stands out on the back of the abdomen. The length is about 10 mm, and about 30 mm when the legs are widened.
Only females have poisons.

・There are various colors (black, tea, ash), red spots on the abdomen, about 0.7 to 10 mm long
Only females have poisons.

In sunny and warm places, nests are nested in all pits, holes, backsides, and gaps in the ground and artifacts.
Example: The bottom of the planter, the back of the outdoor unit, the back of the bench etc.
When working outdoors, wear work gloves to prevent bites.

Don't touch it with bare hands.
To get rid of it, crush it with shoes or use a commercially available pyrethroid insecticide.
(Please crush the egg scabs because the drug does not work.)

Immediately wash the wound with warm water or soapy water and consult a medical institution.
It is a good idea to bring spiders killed in insecticide etc. for proper treatment.

In most cases, pain is like a needle stabbed by a needle, and the bite may feel fever or red, but it is mild.
However, in rare cases, and even if the hands or feet are bitten, it can cause severe pain in the chest, abdomen and whole body, or convulsions.

Treatment for being bitten by a spider is based on symptomatic treatment.
The number of medical institutions that hold antitoxin in Japan are limited, and are not available in Yokohama.
If the doctor determines that treatment with antitoxin is necessary, it will be coordinated with the medical institution that holds the antitoxin.

[Information about antitoxin]
About redback spider antitoxin (notice of Kanagawa) (PDF: 264KB)
Fact Sheet (PDF: 140KB) on clinical characteristics of Japanese redback spider bites and antitoxin treatment (PDF: 140KB)
Click here for more detailed information. → National Institute of Infectious Diseases homepage "What is the redback spider bite" (external site)

In addition, information such as spiders identified at Yokohama City Inst. of Health is also available in the monthly report of the Institute of Health.
　

Beware of the back spider! （PDF：1,535KB）

For consultation on sanitary pests, please contact Health and Welfare Center Health Sanitation Division in your ward.