Please be careful of the venomous "Black Widow Spider" and "Brown Recluse Spider"

Poisonous spiders such as the black widow and the brown recluse have been found within the city, along with their egg sacs.
The black widow and the brown recluse are designated invasive species, but they have been confirmed throughout Japan and are believed to have established themselves here.
If you find a similar spider in your garden, please do not panic and refer to the extermination methods indicated next for appropriate handling.
Both spiders are timid and non-aggressive, but they are highly venomous, so please be careful not to catch or touch them with your bare hands if you find them.
They will not bite unless provoked, but if bitten, wash the affected area with water and seek medical attention as soon as possible.

Control Methods

In addition to using commercially available pyrethroid insecticides, you can also eliminate them using physical methods such as pouring boiling water or crushing them with your shoes (since the egg sacs are not affected by the chemicals, please place them in a bag and crush them before using the insecticide).
If you crush an egg sac with your shoe, make sure to wash the sole thoroughly to prevent any remaining egg sacs from hatching into spiders.
Also, if you find one, there may be more lurking nearby, so please be cautious and check carefully.

Symptoms When Bitten

It is said that a pain like being stabbed with a needle is felt, and the pain spreads beyond the area that was bitten.
Symptoms such as muscle pain and headaches may persist for several weeks.
There have been reports of severe cases such as muscle paralysis, so caution is necessary.

Response in Case of a Bite

In the unlikely event that you are bitten by a spider, please seek medical attention promptly.
If the condition worsens, treatment with antivenom serum may be necessary.
If possible, please bring the dead spider to the hospital so that the type of spider that bit you can be identified.

Characteristics of the Black Widow Spider

• The body length of females is about 7 to 10mm, and the body length of males is about 4 to 5mm (body length refers to the length from the tip of the head to the tip of the abdomen, excluding the length of the legs).
• Only the females are highly toxic and harmful; the males are not toxic.
• The entire body is a glossy black color, with a prominent red vertical stripe on the back of the large spherical abdomen.
• There is a red hourglass-shaped pattern on the abdomen.
• Inhabits places with good sunlight and warm spots, such as shadows and gaps.

Characteristics of the Gray Spider

• The body length of females is about 7 to 10mm, and the body length of males is about 3 to 4mm (body length refers to the length from the tip of the head to the tip of the abdomen, excluding the length of the legs).
• Only the females are highly toxic and harmful; the males are not toxic.
• The colors are varied, with a round body in gray or brown, and spots with a border scattered on the dorsal side of the abdomen.
• There is a red hourglass-shaped pattern on the abdomen.
• Inhabits places with good sunlight and warm spots, such as shadows and gaps.

To avoid being bitten by spiders

The Brown Widow Spider and the Gray Widow Spider can be found in urban areas in small gaps such as the grates of roadside ditches, the joints of wire fences, under vending machines, and in trash cans. They may also attach themselves to umbrellas, clothing, toys, etc., that are left outdoors and be brought indoors.
During extremely cold periods, they can survive in small spaces with insulating objects, and during hot periods, they can live in small spaces with better insulation, making it possible for them to inhabit throughout the year. To create an environment that is less hospitable to spiders, regularly clean areas where spiders might reside.
Only the female is venomous, and if bitten, one may feel a sharp pain similar to being pricked by a needle. In severe cases, the pain may spread throughout the body and could be accompanied by nausea and headaches.
You can kill them by spraying commercially available household insecticides. Additionally, when working outdoors, such as cleaning or maintaining flower beds, wearing rubber gloves can provide protection.

• Ministry of the Environment Natural Environment Bureau Website "Invasive Species Act"(External Link)
• Ministry of the Environment created flyer "Beware of the Brown Widow Spider and the Gray Widow Spider!" (PDF 389.1KB)