About the Myth that Male Ladybugs Mate with Dead Females for Hours Without Realizing It

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Claim:

Male ladybugs can mate with dead females for hours before realizing it.

Rating:

Rating: Unproven
Rating: Unproven

Context:

According to some scientific and anecdotal evidence, there have been instances of male ladybugs mating (or attempting to mate) with their deceased female counterparts for hours. However, there's no proof of the behavior being a distinct characteristic of ladybug mating. Also, there's no evidence of ladybugs "realizing" anything, much less that a counterpart is dead during a mating session.

 

Male ladybugs, also known as lady beetles or ladybirds, can spend several hours mating with dead females before "realizing" something isn't quite right. At least that's what several posts across various social media platforms have claimed over the years, including the TikTok video below:

According to some scientific and anecdotal evidence, there have been instances of male ladybugs mating with their deceased female counterparts for hours.

However, while the behavior has reportedly happened, there's no proof of the behavior being a distinct characteristic of ladybug mating. It's unclear to what extent it occurs in the wild and across the more than 5,000 species of ladybug globally. Also, there's no evidence of ladybugs "realizing" anything, much less that a counterpart is dead during a mating session.

For those reasons, we have rated this claim "Unproven."

Matthew Van Dam, an entomologist and beetle specialist at the California Academy of Science, told Snopes this rumor about ladybugs is largely "unfounded" — that is, it seems based on "anecdotal observations [rather] than any real trend or consistent behavior."

Snopes traced the rumor to an April 1, 1995, article published by New Scientist, a weekly science magazine. The article was titled, "Spot the Ladybird" (archived):

MALE ladybirds are pretty stupid. They can spend up to four hours mating with a dead female before realising something is wrong. And if these cold-blooded creatures get caught in the act when the Sun goes down, the falling temperatures may leave them immobilised till morning. Such tales about one of the world's most cherished insects might scandalise ladybird lovers. Yet they come from an ardent admirer who should know. Michael Majerus, a naturalist at the University of Cambridge, is the founder and coordinator of the Cambridge Ladybird Survey, an extraordinary study of the activities of ladybirds in Britain.

Nowhere in the article did the author provide peer-reviewed, scientific evidence to corroborate the claim that male ladybugs may mate with dead females for hours "before realising something is wrong." (According to Van Dam, the assertion is "more clickbait to get people to read the article.")

The article references the Cambridge Ladybird Survey founded by former Cambridge professor Mike Majerus, whose work contributed to a bigger citizen-science project, the European Ladybird Survey. That program allows anyone in Europe to record ladybug sightings through an Apple or Google app, or the project's website, so that scientists may assess trends over time.

Snopes contacted the organization with a request to access purported observations corroborating the claim that male ladybugs have mated with dead females in the wild. We will update this article when, or if, we receive a response.

Though citizen scientists may have recorded males mating with deceased females for hours, Van Dam said there isn't empirical evidence to suggest males are "any more 'stupid' than the females" — or, that they would exhibit that behavior on the regular considering the biological effects of mating.

In the biological world, there are costs to mating. For example, some species belonging to a New Guinean family of marsupials collapse and die after intercourse. For female octopuses, laying a clutch of eggs will be her final act.

In short, reproduction involves allocating energy and resources through courtship, mating, fertilization, egg production and laying, birthing, and more.

Van Dam referenced a 2013 peer-reviewed research article titled, "Extreme Costs of Mating for Male Two-Spot Ladybird Beetles," which described the mating and sexual selection of male, two-spot ladybug beetles. Mating, the researchers found, is a costly endeavor for two-spot male ladybugs; A single mating session can reduce a male's life by more than half (53%) — the highest of any species, at least at the time of the study.

In other words, at least in the case of two-spot ladybugs, fruitless mating between living males and dead females wouldn't make evolutionary sense. 

Contrarily, researchers in 2023 investigated the "necrophilic behavior" in males of the Harmonia axyridis species, a ladybug native to Asia. (The U.S. considers it an invasive species.)

The researchers found male ladybugs preferred to mate with living females; however, the males would, from time to time, attempt to mate with seven or 14-day-old female carcasses.

But, as the study noted, the experiment was conducted "under laboratory conditions" and such occurrences of males trying to mate with carcasses "should be evaluated in a future study."

And though researchers observed male ladybugs trying to mate with dead females, the study was not designed to distinguish whether they were able to, uhm, complete their mating attempt. That completion would "confirm an extremely high physiological costs of such behavior," the study said.

Sources:

alertLeaveV8. "🦯🐞 - al Male Ladybugs Can Spend Hours Mating with a Dead Female before They Realize Something's Off." America's Best Pics and Videos, https://americasbestpics.com/picture/al-male-ladybugs-can-spend-hours-mating-with-a-dead-c4hTED8rA. Accessed 29 June 2024.

Alexander, Christine. Professor Mike Majerus [1954-2009]. 23 Aug. 2013, https://www.gen.cam.ac.uk/research-groups/mike-majerus.

#author.fullName}. "Spot the Ladybird." New Scientist, https://www.newscientist.com/article/mg14619714-300-spot-the-ladybird/. Accessed 29 June 2024.

Cost of Reproduction - an Overview | ScienceDirect Topics. https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/cost-of-reproduction. Accessed 29 June 2024.

European Ladybird Home Page | European Ladybirds. https://european-ladybirds.brc.ac.uk/. Accessed 29 June 2024.

Harmonia Axyridis. https://biocontrol.entomology.cornell.edu/predators/Harmonia.php. Accessed 29 June 2024.

Ladybug | San Diego Zoo Animals & Plants. https://animals.sandiegozoo.org/animals/ladybug. Accessed 29 June 2024.

Parking, Directions &. and (415) 379-8000. IBSS | California Academy of Sciences. https://www.calacademy.org/staff/ibss. Accessed 29 June 2024.

Perry, Jennifer C., and Crystal T. Tse. "Extreme Costs of Mating for Male Two-Spot Ladybird Beetles." PLOS ONE, vol. 8, no. 12, Dec. 2013, p. e81934. PLoS Journals, https://doi.org/10.1371/journal.pone.0081934.

Řeřicha, Michal, et al. "Mating with Dead Conspecifics in an Invasive Ladybird Is Affected by Male Sexual Fasting and Time since the Female's Death." Frontiers in Ecology and Evolution, vol. 11, Oct. 2023. Frontiers, https://doi.org/10.3389/fevo.2023.1225998.

What Causes the Octopus Death Spiral? New Study Points to Changes in Cholesterol Production | University of Chicago News. 17 May 2022, https://news.uchicago.edu/story/what-causes-octopus-death-spiral-new-study-points-changes-cholesterol-production.