第 0631 號，共 1 402 號

Western black widow

Latrodectus hesperus

需要看醫生很少致命，但被咬了需要看醫生。

咬吃：肉

The western black widow is a venomous spider that lives in western North America. The female is black, often with a red hourglass mark on her belly, and her webs are tangled and irregular. Her venom is strong, so it is worth knowing what she looks like.1

分布在

Western North America: south-western Canada (British Columbia to Manitoba), the Pacific Coast, Texas, Oklahoma, Kansas, and Mexico1

北美洲

首頁

It builds tangled webs low above the ground. It is commonly found near the Canada-US border and less commonly across the grasslands of the Canadian Prairies.1

長度

1,4 cm 到 1,6 cm (0,6 in 到 0,6 in)1

最高速度

大約 0,98 km/h（0,61 mph）

在陸地上, 粗略估計

牠吃什麼？

It hangs upside down near the centre of its web and waits for insects to land in it. It bites the prey, injects venom, and wraps it in silk. Beetles and ants, wasps and bumblebees make up most of its prey.1

Western black widow 的照片 — Western black widow。照片：Luke Padon。 CC BY 4.0, iNaturalist.

怎麼認出牠

The female is about 14–16 mm long and black, often with an hourglass-shaped mark on the lower abdomen.1
The hourglass mark is usually red, but it can be yellow and, very rarely, white.1
The male is about half the female's length and is generally beige, with lighter striping on the abdomen.1
Its webs are irregular or tangled, with no obvious overall pattern.1

常被誤認為： It was once described as a subspecies of Latrodectus mactans and is closely related to the northern species Latrodectus variolus.1

毒液力量

咬

咬的時候，毒液會從毒牙或牙齒出來。

牠的毒液有什麼作用？

The female's venom contains a neurotoxin called α-latrotoxin, which attacks the nerves. In humans, its symptoms include pain, nausea, vomiting, goosebumps and localised sweating.1

牠對人有多危險？

對人的危險: 嚴重被咬了需要看醫生。死亡案例非常罕見。

Historical reports gave fatality rates between 0.5% and 12%. However, recent studies have not been able to confirm any deaths from the U.S. species of Latrodectus, including zero deaths among 23,409 documented bites from 2000 through 2008.1

牠害怕時會做什麼？

Juveniles and females can fling a sticky ball of silk at predators, which can stop most of them.1

如果牠咬人

清洗咬傷處，用冰敷袋冰敷止痛。如果很痛、疼痛擴散或傷者覺得不舒服，要就醫。

一定要先打緊急電話（112、000、911）。這是一般急救指引，不是醫療建議。急救基本知識

注意安全

絕對不要碰、抓或捉弄野生動物，就算是很小的動物，就算牠看起來在睡覺或已經死了也一樣。
給牠空間。如果遇到了，保持冷靜，慢慢往後退，讓牠自己離開。
如果被牠咬了：保持冷靜，保持不動，打緊急電話（112、000、911）或趕快去醫院。記住牠的樣子，有照片會很有幫助。

牠不是想來抓你。牠用毒液來捕捉食物或保護自己，而且牠更想躲起來。更多安全知識

在世界上的哪裡？

非洲亞洲歐洲北美洲南美洲澳洲與大洋洲

牠有多大？

牠有多長？

比你的小指頭還短

Western black widow 跟「你」比起來有多大？

只是在你的瀏覽器裡做算術。什麼都不會儲存，也不會傳送到任何地方。

牠有多快？

一隻陸龜 大約 0,3 km/h (0,19 mph)

Western black widow 大約 0,98 km/h (0,61 mph)

一個正在走路的人 大約 5 km/h (3,1 mph)

值得知道

小知識

When prey hits a gumfoot thread, the thread breaks and creates tension that pulls the line and prey up to the spider.1

This spider is an opportunistic cannibal, and it may eat other members of its own kind when prey is scarce, when it is very hungry, or in self-defence.1

The silk is strongly sticky, and its strength is similar to that of silk from orb-weaving spiders.1

Males can be preferred by females based on the webs, with well-fed females chosen over starved ones.1

Males may mate several times during their relatively short lives.1

破解迷思

迷思： A black widow bite is usually deadly.

真相： Recent studies have not confirmed any deaths from the U.S. species of Latrodectus, including zero deaths among 23,409 documented bites from 2000 through 2008.1

給毒液專家

學名: Latrodectus hesperus
類群: 蜘蛛
家人: Theridiidae2
排序: Araneae
各大洲: 北美洲
寶寶: Females produce egg sacs, and the young are born in the months from May to October.1
對人的危險: 3 / 5: 嚴重3