Beware of the spider

Redback spiders and redback spiders are basically non-aggressive but have poisonous 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 habitat has expanded and 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. Redback spiders were also discovered in 2015, 28, 2019, 2020 and 2021.

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

・Colors vary (black, tea, ash), red spots on the abdomen, about 0.7 to 10 mm in length
Only females have poison.

Nests are nested and hidden in all pits and holes, backsides and gaps in the ground and artificial objects in a sunny and warm place.
Example: Bottom of planter, back of outdoor unit, back of bench, etc.
When working outdoors, wear gloves to prevent bites.

Don't touch it with bare hands.
To get rid of them, crush them with shoes or use a commercially available pyrethroid insecticide.
(Egg sacs are not effective, so please crush them.)

Immediately wash the wound with hot 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, there is pain like a needle stab, and the bite can feel heat or turn red, but mild.
However, rarely severe and can cause severe pain or cramps in the chest, abdomen and whole body even if the hands or feet are bitten.

Treatment for bites by spiders is basically symptomatic treatment.
The number of medical institutions that own antitoxins in Japan is limited, and not in Yokohama.
If the doctor who visits determines that treatment with antitoxins is necessary, it will be coordinated with a medical institution that has antitoxins.

[Information on Anti-Toxins]
About redback spider antitoxins (Notice of Kanagawa Prefecture) (PDF: 264KB)
Fact Sheet (PDF: 140KB) on the clinical characteristics of redback spider bites and anti-toxin treatment in Japan
Click here for more information. → National Institute of Infectious Diseases homepage "What is redback spider bite?" (outside site)

Information on spiders, etc. identified by Yokohama City Inst. of Health is also posted in the monthly report of the Institute of Health Inspection Information.
　

Beware of the spider! （PDF：1,535KB）

If you have any questions about sanitary pests, please contact Health and Welfare Center Health Sanitation Division in your ward.