American Thanksgiving not only marks the beginning of left-over turkey sandwich season, but has also come to represent the official start of the Holiday Season™. Traditionally rung in with the rampant purchasing of sale-priced items, the beginning of Holiday Season™ is now celebrated instead with Black Fly Day. This year, in preparation for ugly sweater parties and more family gatherings than should ever occur in such short succession, I present to you 6 fun facts about black flies that will keep your friends and family utterly enchanted!
Simulium (Psilopelmia) bicoloratum from Ecuador (Simuliidae) feasting on my blood.
The response to the jewel beetle field guide has been incredible thus far, with nearly 900 people requesting more than 1300 copies in less than 2 weeks! With all this attention to beetles around here lately, I figured I’d post a little reminder about which insect order still rules these parts.
Proof that 2 parasitic heads are more gruesome than 1. Parasitic flesh/satellite flies (Sarcophagidae) forever entombed as they attempt a late emergence from the abdomen of a captured Buprestis consularis jewel beetle. Photo by Adam Jewiss-Gaines.
We came across this little tragedy while examining and photographing specimens for the field guide, and Adam Jewiss-Gaines did a great job of bringing their sorry plight to life (so to speak) in this image-stacked photo.
I tried to track down what species (or even subfamily) these flies may be, but I couldn’t find any record (in my admittedly quick search) of sarcophagids using Buprestidae as hosts. According to the Manual of Nearctic Diptera Vol. 2, these little guys likely belong to the subfamily Miltogramminae (based on their seemingly bare arista), which are commonly known as satellite flies for their habit of orbiting ground nesting bees and wasps and kleptoparasitizing their collected prey, but I’m unsure whether they will parasitize free-living beetles. If they are in fact members of the Sarcophaginae (some of whom do have bare arista), perhaps these individuals are members of the genus Sarcophaga, species of which have been reared from beetles and various other insects.
Without being able to examine the rest of their bodies, I may never know what these flies are, but I find it fascinating that they matured and began their escape only to be killed and preserved within our collection!
UPDATE Dec. 17, 2012: Never mind about this being a free-living beetle! I double checked the specimen label, and this beetle was actually collected from a Cerceris fumipennis colony in Highland Hammock State Park, Florida, which almost certainly makes these Miltogramminae satellite flies.
I may be nearly useless with moth identification, but this is one I know by heart. Of course, this isn’t really brag worthy since there aren’t many moths with an iridescent blue thorax and yellow head, but I’m working on baby steps here.
Just because I can identify it doesn’t mean I can place it in the correct family however! When I was an undergrad (back in the day when I had to walk 10 miles uphill both ways, etc) I was taught the tiger moths were a family unto themselves. Since then however, they’ve been sunk into the family Erebidae, causing me much confusion.
The Virginia Ctenucha feeds on a variety of grasses and sedges as a caterpillar, and adults are active from late spring to mid summer.
What feeds on Virginia Ctenucha though? Compsilura concinnata, a tachinid fly that was introduced to North America to combat Gypsy moth (Lymantria dispar) in the late 19th and early 20th century. As is wont to happen with poorly understood ecology and introductions, Compsilura concinnata turned out to be a broad generalist, and is right at home within a wide diversity of caterpillar hosts. There’s concern that this “new” parasitoid is a contributing factor to declining saturniid moth populations in eastern North America, but the fly appears to be under heavy pressure from a hyper-parasitoid species of trigonalid wasp, which appears to be keeping fly populations low enough to prevent eradication of native moths.
——— Kellogg, S.K., Fink, L.S. & Brower, L.P. (2003). Parasitism of Native Luna Moths, (L.) (Lepidoptera: Saturniidae) by the Introduced (Meigen) (Diptera: Tachinidae) in Central Virginia, and Their Hyperparasitism by Trigonalid Wasps (Hymenoptera: Trigonalidae), Environmental Entomology, 32 (5) 1027. DOI: 10.1603/0046-225X-32.5.1019
I can’t help but get a little excited about sphinx moths; they’re so big and cool looking that I just can’t resist taking a photo (foreshadowing: expect to see more sphinx moth photos by the end of the week). This individual came in while I was blacklighting at the Rouge Valley BioBlitz, right in the heart of Toronto.
The Waved Sphinx Moth feeds on a variety of plants as a caterpillar, including ash (Fraxinus), privet (Ligustrum), oak (Quercus), hawthorn (Crataegus), and fringe (Chionanthus). and can be found across much of eastern North America throughout the summer.
UPDATE: It turns out my first theory involving oestrid bot flies was full of holes. I’ll leave it up because the biology of the individual parasites is accurate and interesting, but see the bottom of the post for an accurate description of what happened in the photo. I apologize for the misinformation.
Recently, I was catching up on Twitter late at night when @PsiWaveFunction shared a link to a photo on Reddit that stopped me cold in my tracks and that has kept me morbidly fascinated since. I’ve spent the better part of a day thinking about the photo, and I think I’ve pieced together the series of events and organisms that lead to the case of the mystery myiasis. If my theory is correct, this might be one of the coolest cases of parasitism I’ve ever encountered, and features a fly who’s life history beautifully illustrates the intricacies of evolution, another fly that’s threatening the birds which helped Darwin develop his theory of evolution through natural selection, and a bird who is being selected against by the worst possible luck.
Normally I’d include the photo in question right about here, but out of respect for those victims readers who are a tad squeamish at the sight of parasites (or birds), I’ll simply link to it and allow your curiosity to battle your better judgement1. I’ll give you a moment to decide and, should you accept the challenge, digest what you’ve just seen.
So, were you amazed? Disgusted? Wondering what the hell you were looking at? If you’re like me, you probably felt a little bit of all three, and then immediately went back to take a closer look.
Welcome to the wonderful world of warble flies (family Oestridae)! Each of those oddly formed lumps is actually a bot fly maggot which has burrowed beneath the skin of the chick to feed and develop. You’ll notice two dark marks on the exposed end of each maggot; these are the spiracles through which the maggot breathes. After a few weeks, each of the maggots will wriggle free from the bird, drop to the ground and pupate, eventually emerging as an adult ready to breed. Normally the host is left mostly unharmed after providing safe harbour for a bot fly, but in this case I suspect the bird might have problems due to the shear number of maggots present (at least 15 that I could make out).
Dermatobia hominis -- Photo by J. Eibl, Systematic Entomology Laboratory, USDA.
What’s odd about this situation2 is that these bot flies have parasitized a bird. You see, almost all bot flies are mammal parasites, infesting anything from rodents to elephants, and are usually very specific about their host species. One bot fly however, Dermatobia hominis, is a generalist, and has been recorded infesting a number of different animals, from humans and monkeys to dogs and cats, and of relevance to this story, birds on occasion. In a family of narrow specialists, it’s a wonder that D. hominis is such a broad generalist; until you learn how D. hominis distributes its offspring — by hijacking other flies to serve as expedited egg couriers.
Psorophora sp. (Culicidae) with D. hominis eggs attached. Illustration by A. Cushman, Systematic Entomology Laboratory, USDA.
After mating, female D. hominis will snatch up other parasitic flies, like mosquitoes, flesh flies and muscid flies3, and lay a clutch of eggs on the enlisted fly. When the carrier fly locates and lands on a host to feed4, the body heat of the victim signals the bot fly egg to hatch and fall from the carrier onto its new home, where it quickly burrows in to begin feeding. This amazing life cycle means that the female bot fly has little control over where, and on what species, its offspring ultimately end up infesting, resulting in a nearly random generalist parasite that must be able to survive on whatever host it finds itself on, including our small bird.
Obviously the natural world is a complex system, and unfortunately for our bird, it’s full of a diverse array of parasites, all looking for a free meal. Let me introduce you to another player in this saga, Philornis downsi (Muscidae), a fly native to continental South America and Trinidad & Tobago, where our unfortunate bird lives.
Philornis in nasal cavity of deceased bird. Image from O'Connor et al. 2010
While adults are unassuming, feeding on pollen and nectar, Philornis downsi larvae are brood parasites of nesting birds. Hiding out of sight during the day in the bottom of the nest, maggots emerge after dark to crawl within the nasal passages of developing chicks, feeding on their blood and tissue, sapping their energy. As the maggots continue to grow, they begin feeding elsewhere on the nestlings, causing severe damage and ultimately death. Throughout the Galapagos, where the fly was introduced sometime prior to 1964, Philornis downsi has been causing nestling mortality rates as high as 95% in Darwin’s finches, the unique birds who’s diverse beak shapes inspired Charles Darwin’s theory of evolution by natural selection. While there has been a great deal of work done on P. downsi in the Galapagos in an effort to save these ecologically important birds5, I assume it is also receiving research attention in its native range, which is where we return to Reddit, our original photo and what I think happened.
Of all the parasites, in all the nest boxes, in all the world, she flies into mine.
My theory was wrong. See below for information about the actual parasite.
A recently mated female Dermatobia bot fly was looking for a carrier fly
A female Philornis downsi happened to fly by, was quickly snatched by the bot fly and entrusted with a load of bot fly eggs
The female Philornis was released, and continued her search for a bird’s nest to deposit her eggs in
Finding a nest, the Philornis female walked around, laying eggs among the nesting material, and happened to tread across the young bird in the nest
The bot eggs, sensing the proximity of a warm-bodied host, hatched and quickly found their way to the unlucky bird’s face
The Philornis female finished laying her eggs and took off from the nest, leaving chaos brewing in her wake
Later, a social media-conscious research assistant comes along, finds the disfigured nestling, and does the only logical thing; takes a picture and posts it to the internet for all to enjoy!
Of course, this is only a theory based on a single photo and a very small fraction of information about the team’s research, but given the evidence and biology of the species potentially involved, I think it’s certainly a plausible hypothesis. There are a lot of potential fallacies in my theory, like whether the bot fly larvae are actually Dermatobia, or whether Dermatobia even uses Philornis as a vector (although it’s known to use 11 species of Muscidae), but these are the sort of questions that can be observed and tested eventually. Hopefully the researchers behind the photo will rear the maggots from the bird’s face, identify the parasites involved, and then publish their work so I can find out whether any of these ideas turned out to be accurate6.
Whether my theories were correct or not, the fact that they’re even plausible keeps me interested and excited about entomology and the intricate roles parasites play in our daily lives!
Eibel, J.M., Woodley, N.E. 2004. Dermatobia hominis (Linnaeus Jr., 1781) (Diptera: Oestridae). The Diptera Site. Accessed June 6, 2012. http://1.usa.gov/MbTexi
Fessl B, Sinclair BJ, & Kleindorfer S (2006). The life-cycle of Philornis downsi (Diptera: Muscidae) parasitizing Darwin’s finches and its impacts on nestling survival. Parasitology, 133 (Pt 6), 739-47 PMID: 16899139
O’Connor, J.A., Robertson, J. & Kleindorfer, S. (2010). Video analysis of host–parasite interactions in nests of Darwin’s finches, Oryx, 44 (04) 594. DOI: 10.1017/S0030605310000086
UPDATE June 7, 2012 @ 3:30PM EST: It turns out that the maggots in the bird’s face aren’t Dermatobia hominis, or even bot flies of the family Oestridae at all! After doing some further research, I’ve learned that they are more likely to be another species of Philornis fly. I was totally unaware that there were flies outside of the oestrid bot flies which burrow into the skin of hosts and form warbles like these, but it turns out there are.
While Philornis downsi are ectoparasites that feed on nestling birds as I described, it seems that there are several species in the same genus which burrow within the skin and form welts similar to oestrid bot flies. Here’s an example of Philornis vulgaris infesting a Tropical Mockingbird nestling from Colombia:
Philornis vulgaris infestation from Amat et al. 2007
Looks vaguely familiar no? I think it’s safe to say now that this is what happened in the original photo and not the complex tale of 2 parasites like I described above.
I’m incredibly embarrassed by my Taxonomy Fail here (which holds a TFI of 11.3). Although the biology of the two parasitic species I originally discussed are accurate, the chances of them having anything to do with one another appear to be unlikely. I sincerely apologize for publishing a story that spread such inaccurate information, and I’ll do my best to not let it happen again.
Note to self: don’t assume you know anything, especially when it involves parasites.
On the bright side, I learned something new about Diptera (and humility) today, and we can all rest comfortably knowing that there are multiple, unrelated groups of flies that get under the skin of their hosts. Because I’m sure that makes everyone feel better.
More information about subcutaneous Philornis:
Amat, E., J. Olano, F. Forero & C. Botero 2007. Notas sobre Philornis vulgaris (Couri, 1984) (Diptera: Muscidae) en nidos del sinsonte tropical Mimus gilvus (Viellot, 1808) en los Andes de Co- lombia. Acta Zoológica Mexicana, 23(2): 205-207. http://bit.ly/LwsHh1
Uhazy, L.S., Arendt, W.J. 1987. Pathogenesis associated with philornid myiasis (Diptera: Muscidae) on nestling pearly-eyed thrashers (Aves: Mimidae) in the Luquillo Rain Forest, Puerto Rico. Journal of Wildlife Diseases 22 (2): 224-237. http://bit.ly/KlXBGR
1- If you can’t decide, I vote you click and look. You can thank me later.
2- Beyond the whole face-of-a-million-maggots of course.
4- Something these blood-sucking flies have evolved to do quite well obviously. The fact that bot flies “cheat the system” in this regard, getting their eggs to their host without needing to invest energy in complex host-finding senses, just goes to show that nothing is more awesome than evolution in action.
Since a piranha-like fish with 1+ inch teeth isn’t scary enough on it’s own, this one has a frickin’ isopod for a tongue! Big sharp teeth, murky water, and a tongue-replacing parasite: need I say more?
This little beauty was fished from the depths by my labmate Steve Paiero while visiting Guyana in January. I can imagine reeling in this Hydrolycus (I think the fish is either Hyrdolycus armatus or Hydrolycus tatauia) would be exciting, but then to remove the hook and find a parasitic isopod looking back at you? Amazing. Or horrifying. I’m not sure.
Cymothoidae isopods1 are one of the stranger parasites out there, and have garnered considerable attention from other bloggers. After entering the fish’s mouth through the gills2, they begin to suck on the fish’s tongue, drawing all the blood from it. As the tongue withers and dies, the isopod takes its place, and helps itself to any food the fish may happen to ingest, making them an odd combination of parasite turned kleptoparasite!
I could find very little taxonomic or natural history information about these isopods, but there is apparently only 1 species of Cymothoid isopod with a penchant for tongue, Cymothoa exigua [Update: Dr. Alistair Dove (@para_sight) of the Georgia Aquarium informs me there are numerous tongue biting isopods. This is unsettling]. Oddly, all accounts I’ve been able to find list Cymothoa exigua as a marine species, and not something you’d expect to find hundreds of kilometers up a river in the mouth of a freshwater fish! Seeing as it has a few more legs than I’m used to dealing with, if someone has a better idea on what’s going on, I’d love to hear about it.
Needless to say, I’m glad I’m not a small guppy potentially staring this in the face one day!
UPDATE April 11, 2012: It seems there are a mouthful of tongue biting isopods in South American freshwater ecosystems. I’m in the process of doing a little more research and will update the identity and biology when I can!
1- That’s right, this beastie is a cousin of the innocuous little pill bugs (sometimes called potatoe or sow bugs) that you can find in your own backyard.
2- You can see another little isopod latched on to the right side of the mouth in both photos. Whether this is an immature Cymothoa exigua or a different species I’m not sure. Either way, tough luck for the fish!
It’s not often that flies make headlines, and when they do it’s usually in a negative connotation (malaria, mosquitoes, black flies, etc). A new paper published Tuesday in PLoS ONE (Core et al, 2011) is certainly not helping this Detrimental Diptera Dillema (DDD), announcing that a species of scuttle fly (Phoridae) has been discovered parasitizing honey bees (Apis mellifera), one of the most loved insects on the planet.
Fig. 2 - Images of Apocephalus borealis and honey bees from Core et al., 2012
Of course things attacking honey bees isn’t in itself news, especially in the age of Colony Collapse Disorder (CCD). The real news here is that the scuttle fly, Apocephalus borealis, has seemingly switched hosts, previously known to be parasitic in bumble bees, paper wasps, and even black widow spiders (Brown, 1993). Other Apocephalus flies are better known as ant-decapitating flies, who’s larvae will pupate in the dismembered heads of their ant hosts. As for A. borealis, it’s association with honey bees was thanks to a serendipitous natural history observation:
(John) Hafernik, who also serves as president of the California Academy of Sciences, didn’t set out to study the parasitized bees. In 2008, he was just looking for some insects to feed the praying mantis that he had brought back to SF State’s Hensill Hall after an entomology field trip. He scrounged the bees from underneath the light fixtures outside the biology building.
“But being an absent-minded professor,” Hafernik joked, “I left them in a vial on my desk and forgot about them. Then the next time I looked at the vial, there were all these fly pupae surrounding the bees.”
After further observation, a few behavioural trials and some interesting molecular techniques, the research team found that not only were these scuttle flies parasitizing honey bees in the San Francisco Bay area, but also in migratory bee colonies housed in the Central California Valley and South Dakota, and also that infected honey bees would leave their colonies at night to fly away and die (often congregating at man-made lights and acting strangely); that all of the parasitized bees had been exposed to Nosema ceranae (a fungus which can lead to death from diarrhea and malnourishment) and/or Deformed Wing Virus (a disease that can cause malformation of a bee’s thorax and wings during pupation); and that some of the flies had evidence of these bee pathogens in their systems.
This is a lot of really interesting information for one study, but it’s not hard to see where the authors were going next with their story: scuttle flies could be contributing to CCD and posed a “new threat” to honey bees. The authors proceeded to pose a long series of questions regarding future areas of research, and how all of their findings could be detrimental to honey bee populations and the potential role these flies play in CCD. Overall, this is a very cool piece of natural history research, with a bit too much CCD hype for my liking!
You can see why the media has fallen in love with this paper; it includes flies (which no one likes on principle), honey bees (which everyone likes on principle), CCD (which scares the daylights out of everyone) and zombies (which also scare the daylights out of everyone). At the time that I wrote this post (midnight-ish Wednesday morning), I found 13 major news outlets or blogs from around the world which had covered the story (see list below).
This is where we have a problem though. Of the 13 stories I looked at, 8 of them had errors in their reports, of varying severity. What’s worse, all of the erroneous accounts were in major reporting outlets, potentially misinforming thousands of readers! It’s not surprising however, to see that 7 of the 8 stories that got things 100% correct were all science-focused publications/blogs, while one was a small-market news affiliate:
KQED News – ‘Zombie’ Parasite Preys on Bay-Area Honeybees, by Lauren Sommer
MSNBC (WebCite copy) – Stated bees which foraged at night were more likely to be parasitized than bees that foraged during the day (misinterpretation of Fig. 3A of Core et al., 2012)
Mirror (WebCite copy) – Stated that the parasite “is similar to one being found in bumblebees” (it’s not just similar, it’s the same species)
Press Association (WebCite copy) – Title states that the flies are linked to bee losses (not true, the connection between fly parasitism and CCD is simply proposed by the authors); Implied that bees are immediately turned into light-seeking zombies after the female fly lays her eggs (it appears to take up to a week for this to happen)
Daily Mail Online (WebCite copy) – Title states link between flies and global decline of bees (see above); Didn’t italicize species names (minor I know, but it bugs me)
CBC News (WebCite copy) – Implies that bees which foraged at night were more likely to be parasitized than bees that foraged during the day (see MSNBC)
io9 (WebCite copy) – “This parasite is a likely culprit (in reference to CCD – MDJ) because it does indeed force bees to abandon their colony” (authors say the fly may contribute to CCD, not that it is the likely culprit)
Daily Express (caching not allowed) – Implies that bees are parasitized in their hives and that they immediately “abandon their hives in a crazed state” (the authors are unsure of where the flies attack, but they know it’s not in the hive, and see the Press Association above); didn’t italicize species names (argh)
While I doubt that heads will roll at these institutions because of these errors (sorry, a little Apocephalus humour there), the moral of this story is that the science content the majority of the public is exposed to is not exactly the best science content available! Hopefully, as scientists and science writers continue to use social media and blogs, the good stories I featured here will reach more of the people who would normally only see the “bad” versions, imparting a correct and positive experience with the fantastic research being done every day around the world!
Update (Jan. 07, 2012, 20:30) Brian Brown, a co-author on this study and the world’s expert on these flies, has expanded on the natural history and taxonomy of the flies involved in this research on his blog ‘flyobsession’. The remainder of the research team behind this study will be setting up a FAQ to help ‘clarify’ some of the errors I reported on above, and are also beginning a new citizen science project to begin understanding how far flung this parasitism is.
Core, A., Runckel, C., Ivers, J., Quock, C., Siapno, T., DeNault, S., Brown, B., DeRisi, J., Smith, C., & Hafernik, J. (2012). A New Threat to Honey Bees, the Parasitic Phorid Fly Apocephalus borealis PLoS ONE, 7 (1) DOI: 10.1371/journal.pone.0029639
Today’s special guest blogger is Jess Vickruck, a PhD candidate at Brock University. Jess studies twig nesting bee diversity and the impacts of nest choice on their biology.
When I first started my master’s project, my intention was to look at how nest choice affected fitness in twig nesting carpenter bees (genus Ceratina, family Apidae). Little did I know that along with twigs full of bee larvae I would also get up close and personal with numerous uninvited house guests who all had one thing in mind – Ceratina are delicious! Although my supervisor continually reminded me that my thesis was about the bees and not the species that eat bees, I wrote up the data, and lucky for me it appears in the 2010 edition of the Journal of the Entomological Society of Ontario.
Today started good and early while we got our gear repacked to head to the northwestern region of the country to spend a few days in the Guanacaste Conservation Area. The tour bus picked the people from our hotel up shortly before 8, and after a minor detour back to pick up the forgotten, we were on our way north! Unfortunately I slept most of the way up, and when I wasn’t sleeping I was writing blog posts, but there were some rather remarkable landscapes and sections of habitat that we drove through. The most impressive was probably Rincon de la Vieja, an active volcano that reached high into the clouds and had some fantastic secondary outcroppings in the foreground. We stopped for lunch in Liberia, and fended off the honey bees (Africanized perhaps?) throughout the course of our buffet meal. We arrived at the Guanacaste Conservation Area around 2:30 and quickly got ourselves set up in our rooms and ready to jump into the jungle. Within minutes of leaving the main station we had seen 2 troops of white-faced spider monkeys, and a lone howler monkey hanging out in the tree tops. Although the clouds had rolled in and the tropical sun was starting to go down, we still had a number of interesting insect finds, if not flies. Dinner was pretty good, better than predicted at least, and we then sat down and introduced ourselves and pointed out which families we work on and which we’d like material, it was pinning any insects we may have found and some cards before bed. The station and habitat around here looks great, so it should be a really exciting week of collecting.
On the way back to the lodge we ran into Dan Janzen and Winnie Hallwachs, two big-time ecologists who are currently trying to identify every moth, skipper and butterfly within the conservation area using DNA barcoding. They had just run across a boa, which we couldn’t refind unfortunately, but hopefully we’ll see more in the next few days!
It wouldn’t be ACG without a heavily parasitized caterpillar: