New Parasitic Wasp Rides on Bigger Bug (Video)

Talk about a helicopter parent—a newfound species of wasp rides on the back of a bigger flying insect to help its offspring, a new study says.

wasp picture
The newfound wasp clings to the back of a damselfly. Image courtesy Andrew Polaszek, Natural History Museum

Named Hydrophylita emporos—emporos is Latin for “passenger”—the female wasps were observed clinging to abdomens of damselflies, an aquatic insect related to a dragonfly. This acrobatic feat eventually pays off: When the damselfly starts laying its eggs on a submerged leaf, the wasp walks down the abdomen of the damselfly like it’s an exit ramp, enters the water, and then lays its own eggs in the damselflies’ eggs. (See “‘Zombie’ Roaches Lose Free Will Due to Wasp Venom.”)

Watch a video of the wasp climbing on the damselfly.

This is “very clever” on the part of the wasp: The quicker access to fresh eggs, the better for the wasp, said study co-author Andrew Polaszek, head of the Division of Terrestrial Invertebrates at London’s Natural History Museum.

Weird Wasp

Study leader Yuan Tung Shih first saw the wasp-on-damselfly behavior in the wild in Taipei, Taiwan, and told his adviser Polaszek, who was amazed but needed proof. When Shih sent him specimens and a video of the behavior, Polaszek “knew it was something special.”

The new wasp has unusually long antennae compared with its relatives. Image courtesy Andrew Polaszek, Natural History Museum

“I’ve got 25 years of experience doing this, and when I looked at these things I didn’t know what family they belonged to,” said Polaszek, who eventually placed it in Trichogrammatidae, the family of the smallest known insects—the tiniest is 0.17 millimeter.

For one thing, H. emporos looks nothing like other wasps in its genus—it has long, delicate features instead of the “short, stumpy” antennae and legs of its relatives—differences that are still unexplained, he said. The females also have bigger “claws” than other wasps, perhaps an adaptation to walk in freshwater currents.

The wasp’s relative ease in living both in and out of water also surprised the team. For instance, some H. emporos never leave the water after hatching—males, which appear to be very rare at about 125 females for one male, likely stay underwater their entire lives, according to the study, published July 24 in the journal PLoS ONE. (Read: Parasitic Wasp Swarm Unleashed to Fight Pests.”)

Other parasitic wasps ride on their hosts—it’s a practice called phoresy—but it’s the first time it’s been seen in the Hydrophylita genus, Polaszek added.

Intriguing Questions

Robert Matthews, a professor emeritus of entomology at the University of Georgia, pointed out by email that the newfound wasp and others in its family are notoriously weak fliers, whereas damselflies are agile and highly mobile fliers.

wasp drawing
A drawing of the newfound wasp. Image courtesy Andrew Polaszek, Natural History Museum

So by hitching a ride, the newfound wasp has “neatly solved the problem” of how to access new hosts with little apparent risk, said Matthews, who was not involved in the study.

But intriguing questions remain, Matthews said, including what cues the wasp receives before it jumps on a damselfly—for instance, how does the wasp know whether it’s a male or a female damselfly? (Also see “Wasps Can Recognize Faces.”)

What’s more, he’s curious about why there are so few males. “Mating behavior,” he said, “will likely prove to be interesting.”

Christine Dell'Amore, environment writer/editor for National Geographic News, has reported from six continents, including Antarctica. She has also written for Smithsonian magazine and the Washington Post. Christine holds a masters degree in journalism with a specialty in environmental reporting from the University of Colorado at Boulder. Her book, South Pole, was published in 2012.
  • imen

    this scientific fact ressently found we know it us muslim before 1400 years according to the coran in wich god said”إِنَّ اللَّهَ لَا يَسْتَحْيِي أَنْ يَضْرِبَ مَثَلًا مَا بَعُوضَةً فَمَا فَوْقَهَا ۚ فَأَمَّا الَّذِينَ آمَنُوا فَيَعْلَمُونَ أَنَّهُ الْحَقُّ مِنْ رَبِّهِمْ ۖ وَأَمَّا الَّذِينَ كَفَرُوا فَيَقُولُونَ مَاذَا أَرَادَ اللَّهُ بِهَٰذَا مَثَلًا ۘ يُضِلُّ بِهِ كَثِيرًا وَيَهْدِي بِهِ كَثِيرًا ۚ وَمَا يُضِلُّ بِهِ إِلَّا الْفَاسِقِينَ
    wich means”God does not shy that cites the example of a mosquito and above those who believe they shall know that right from their Lord, and those who disbelieve say what God wanted this, for example, it very much astray and give it so much and only folk astray

  • Colleen Smith

    I just took a picture of a bee in my butterfly garden the other day. When I downloaded it and zoomed in, I realized there was what appeared to be a tiny bee sitting on it’s back; it was hard to tell because it wasn’t an extremely clear shot. I thought I was seeing things at first…but this may just explain it!

  • Andrew

    The biological world is truly epic in it’s nature.

  • Benjamin

    “So nat’ralists observe, a flea
    Hath smaller fleas that on him prey;
    And these have smaller fleas to bite ’em.
    And so proceeds Ad infinitum.”
    Jonathan Swift

  • Yvonne Morris

    This is amazing ! …. and very interesting Questions, especially why there is a ratio of just one male to 125 female. I wonder if it has to do with the amount of dangers a female encounters during her life span, while the male eventually remains in the relatively safe environment under water …. Does the male live longer than the female ? If the male does not leave the water, they must mate under water, so the male is most likely bound to a small radius of a habitat. How does their life cycle look like ? How does the injected Wasp larvae effect the hosts offspring ? ….. so many Questions !!!!

  • Yvonne Morris

    The wasp might not be able to recognize the difference between male or female host / carrier insect, but that also would explain the ratio difference, because many female would just waist their life away sitting on a for them useless male …… that could be a reason to have so many more female, because just a few of them will find a female carrier insect …… ???

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