Second ant-decapitating fly found in Glendale

Photo of Pseudacteon amuletum by Phyllis Sun.

Back in November, Lila Higgins of the Natural History Museum posted an eye-grabbing headline on the museum's blog: Ant-decapitating Fly Found in Glendale! Lila is a bug person who has advised me on the existence of firefly-like creatures in Los Angeles, and who doesn't seem to over-excite easily, so this caught my attention. But I failed to post for whatever reason. Then the moment passed. Now today comes a headline I can't ignore: Second Ant-decapitating Fly Found in Glendale. OK, entomology people of Exposition Park, tell us about it.

Our scientists found another species of ant-decapitating fly in Glendale, Pseudacteon amuletum!

For those of you who missed Lila’s exciting account of the moment Dr. Brian Brown first spotted an ant-decapitating fly in one of our BioSCAN samples as it was being sorted in front of our visitors in the Nature Lab, please enjoy this post. As Lila so eloquently described, ant decapitating flies are tiny but mighty little phorid flies that lay their eggs inside of the bodies of, you guessed it, ants. Many of these specialized flies have been the focus of our Entomology Department’s research as conducted in other, more tropical locales, so it may come as a surprise to hear that we have these incredible phorids right here in L.A. These parasitoids (a term we use to describe organisms that eventually consume and kill their host) will not just lay an egg in any ant they come across, but instead target a particular species.

For instance, Pseudacteon californiensis, the first ant decapitator to turn up in a BioSCAN sample, preferentially seeks out the native velvety tree ant, small ants with an orange thorax that nest beneath bark and in tree cavities. Some ant decapitating flies, like zombie hunters, “aim for the head,” [emphasis added] but P. californiensis has been observed hovering over the abdomens of velvety tree ant workers where they appear to “lift” the abdominal segments to insert an egg into the host. The larvae must then travel towards the head, making their way through the occipital foramen (the very narrow opening containing the connective tissue between the thorax and head), to complete their development in the head capsule, which eventually is separated from the body by enzymes released by the developing maggot.

Our second Pseudacteon discovery from the same site in Glendale is P. amuletum, named from the Latin word for amulet due to its distinct horseshoe shaped oviscape that is reminiscent of a charm or pendant. One may also infer a deeper meaning of the name beyond shape but also of function: amulets can protect, and this species of Pseudacteon is important as a form of biological control against fire ants.

There's more at Nature at NHM.