Female black widow spiders start EATING their mate before they even finish mating

Female black widow spiders begin to eat their mate during sperm transfer during copulation, a new study shows.

Researchers in Canada have described the disturbing mating behavior of a species of black widow spiders endemic to South America called Latrodectus mirabilis.

Cannibalism between the two sexes is initiated by females “by grasping and piercing the legs during mating,” lab observations have shown.

Overall, 70 percent of females connibalized their first mate, they noted, but this number rose to 85 percent if the female had mated before.

The recently deceased cannibalized male is also less likely to become a parent, as the female is then free to mate with other males.

Gruesome video footage shows an unlucky man who in his last moments is shadowed by his relatively gigantic lover.

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Images of female and male Latrodectus mirabilis during mating trials. In the early stage of mating, the female grasps the male’s leg (ml) with her chelicerae (fc) and pierces it with her canine teeth. The belly of the man (mom) is also marked


Scientists in Miami have found a new species of spider that looks like a “little shiny black tarantula” and has a venom that, like a bee, causes painful stings.

The Pine Rockland trapdoor spider (Ummidia richmond) was first found by a zookeeper on the grounds of Zoo Miami in Florida.

With legs outstretched, the male is about the size of a one-pound coin, while the female is estimated to be two to three times larger.

Ummidia is a trapdoor spider – meaning it lives in a burrow with a hinged lid like a trapdoor to hide from predators and grab unlucky prey.

Read more: Terrifying New Spider Species Discovered in Miami

Sexual cannibalism in insects and arachnids is well documented and usually the dominant female kills and eats the male after mating.

In general, the benefits of sexual cannibalism may include obtaining food for reproduction or encouraging males to avoid mating with inferior females, previous studies have shown.

From the male’s point of view, it is evolutionarily beneficial for him to sacrifice himself for the well-being of his mate and his offspring, who benefit from his essential nutrients.

“Usually there are some benefits to the male of being eaten during mating, such as longer copulations and reduced female receptivity to future males,” study author Luciana Baruffaldi of the University of Toronto Scarborough told New Scientist.

“In this case, however, we don’t yet know how the man benefits from sexual cannibalism.”

For the study, Baruffaldi and her colleague collected male and female L. mirabilis juvenile spiders from the field in Piedras de Afilar, Canelones, Uruguay.

The specimens were then kept in plastic cages at room temperature at the Clemente Estable Institute of Biological Research in Montevideo, Uruguay.

Their development was monitored and the date they reached sexual maturity was recorded before males and females were introduced to each other and their interactions filmed and analyzed.

In the later stage of mating, the female pierces the male's abdomen (ma) with her fangs while grasping the male's body with her chelicerae (fc), and the male's legs are wrapped in silk (s)

In the later stage of mating, the female pierces the male’s abdomen (ma) with her fangs while grasping the male’s body with her chelicerae (fc), and the male’s legs are wrapped in silk (s)


Study author Luciana Baruffaldi of the University of Toronto Scarborough told MailOnline what happens in the video above.

The poor male was sexually cannibalized by the female during mating.

The female began by grasping and ‘piercing’ the male’s leg with her chelicerate, then added more silk to the other male’s legs and pulled the male’s abdomen towards her chelicerate and pierced it with her fangs while she was mating,” she explained.

Adult females were placed in mating arenas sometime between 24 and 48 hours to build webs before the males were introduced.

A total of 21 unpaired females were mated to adult males – and only one of the females was not “actively courted.” Of the remaining 20, all females copulated at least once.

Nine out of 20 matings ended with just one mating, mainly due to: the female sexually cannibalizes males during the first mating.

Cannibalism began during copulation when females grabbed the male’s legs with their chelicerae — their strong, fang-bearing front appendages — and pulled the belly of the males to their mouths to eat them.

In a second round of experiments, the team found that 85 percent of the previously mated females cannibalized their second mate.

Interestingly, sperm transfer is not prevented by cannibalism, but the fact that females mate with other males “decreases the chance of benefits from cannibalism for males,” the experts say.

Other spiders in the genus Latrodectus practice sexual cannibalism during copulation.

Male redback spiders (Latrodectus hasselti) and brown widow spiders (Latrodectus geometricus) initiate the cannibalism by turning over to “sacrifice” their bellies to the female, Baruffaldi said.

The difference with L. mirabilis is that cannibalism was initiated by females and not facilitated by males like these other species.

The new study, published in Behavioral Processes, describes a unique form of sexual cannibalism not previously reported for gender.


dr. Nathan Burke and Professor Holwell call sexual reproduction “rarely a harmonious affair.”

Sexual conflicts over mating interactions can drive the evolution of behavioral or morphological traits that improve fitness of one sex at the expense of the other.

Typically, sexual conflict promotes coercive traits in males that facilitate mating through violence or intimidation.

In sexually cannibalistic insects where females consume males before, during or after mating, the greater cost is borne by males.

Females can improve reproductive output with the additional nutrients gained from the cannibalization of males, while males lose all future reproductive capabilities if consumed.

Therefore, male mating tactics are required that reduce the risk of cannibalistic attacks.

However, coercion seems to be an exception – males typically use cautious strategies to secure mating and avoid cannibalism.

Examples of such strategies include males using stealth during mating approaches, courting females with a “lure wedding gift,” playing dead when females attack, and preferentially mating with females feeding or moulting.

Rare examples of males mating coercively rather than cautiously can also be found in some sexually cannibalistic spiders.

These courting males immobilize females for mating by biting them, injecting them with venom, expelling chemicals into the air, or tying them with silk.

Such behavior can harm females by causing hemolymph loss or decreased foraging performance.

Source: Burke and Howell in Current Biology

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