Parasites Regained

A few weeks ago, we collected the common grass-bush anole Anolis pulchellus around the El Verde Field Station for an enclosure experiment looking at interspecific interactions. We stored the lizards in baggies in the lab for a day or two, moved them to their enclosures for just under three weeks, and we’ve recently finished recapturing them from the enclosures. After measuring their growth and sampling their diets, we put them back where we found them so they could continue on their way with a great story to tell their friends.

One unlucky anole, however, never made it to its enclosure. When I retrieved its bag to take to the experiment site I found the following tragic scene:

The anole appeared to have basically exploded. It looked like foul play, and unlike in the case of other anole-themed murder mysteries, in this case the culprits were apprehended immediately. This poor little (31 mm snout-vent length) guy had somehow been running around out there despite harboring not just one, but five chunky fly larvae inside him.

Just for fun, I kept the larvae in some moist dirt in a plastic container on my desk. I’d largely forgotten about them, but after about three weeks (and only days before we’re due to leave Puerto Rico), the circle of life was complete. Three of the five larvae emerged as adult flies buzzing around the container.

I’ve spent plenty of time looking at aquatic insect larvae from fish stomachs, but I’ll be the first to admit I know next to nothing about adult insect identification. Some quick googling turned up a study by Irschick et al. (2006) looking at the effects of a parasitic fly on Anolis carolinensis in Louisiana. That parasite was a member of family Sarcophagidae – the flesh flies – and it looks like that’s probably what was living inside the poor anole as well. They certainly have the red eyes and striped backs that characterize Sarcophagids, though if anyone can identify it with more confidence please let us know.

Interestingly, I’d noticed that some of the Anolis pulchellus had bumps or nodules projecting from their bodies. This seemed to be especially common in anoles from higher elevations (400-500 m) – this is where the deceased anole came from, though I didn’t notice if he had bumps too. Has anyone noticed these on other species? I don’t know if there’s any connection to parasite infection, but it’s a suspicious coincidence…

About Travis Ingram

I mostly study freshwater fish ecology and evolution in New Zealand, but I spent two years as a postdoc in the Losos lab looking at the niches of Puerto Rican anoles and working on comparative methods for studying convergence.

11 thoughts on “Parasites Regained

  1. Travis – Way cool! As for the elevation differences in parasite load – this correlates well with what we know from the literature. Zippel et al. (1996) found that A. coelestinus and A. cybotes from higher elevation were more infested than their low elevation counterparts. They attributed this to moisture differences between habitats, rather than elevation, per se. Indeed, this summer we counted ectoparasites for an undergrad’s study and elevation alone does not appear to be the best predictor.

    1. PS: I just now got your reference to Milton. Certainly the poor dead lizard has discovered the burning lake of Pandemonium.

  2. Jason Kolbe, Butch Brodie, Jonathan, & I had a similar incident – I believe also with A. pulchellus – during a field trip back in 2006. If I remember correctly, Jason collected the larvae. – Liam

  3. I’ve seen similar larvae in Anolis carolinensis (at sea level). Some larvae even punctured a hole the skin, as though they needed a hole to breath from, but continued to burrow around subcutaneously. Those anoles were not long for this world.

  4. I have seen similar bumps around the necks of some female A. sagrei on Eleuthera (Bahamas). I wonder if they are related to parasites or if they are just abcesses or calcium deposits…

  5. I live in south TX and have been a great fan of green anolis since I was a child. I’ve been quite distressed that over the last few months I’ve found several dead anolis and seen a few live ones that are apparently are infested with Sarcophagid Fly larvae. I’d never even heard of this fly but research has led me to believe that’s what it is.

    Is this a serious problem, and is there any way to control these flies?

    1. Rebecca,
      there isn’t much known about sarcophagid fly parasitism of lizards, and the little that there is can be found in the paper cited in the post (I can send you a copy if you email me). It is interesting that you have noticed an increased in the frequency, which could suggest that the flies have become more abundant or the lizards more susceptible. Perhaps the drought has weakened the lizards? I’m just guessing. As for controlling them, I suspect we don’t know enough about them to figure out how to do that. However, a quick google revealed that these flies are used by medical entomologists, so perhaps there is more known than I realize.

      1. Thanks, Jonathan. I’m definitely interested in learning more about this situation even if there’s nothing that can be done to control it. I’m still disturbed about this as I’ve never seen anything like it. Sure hope whatever caused this will soon reverse itself. Following is the article I found when first I realized this was going on. In fact, I witnessed an anoli running through the grass being pursued by a fly, and that’s when I first suspected something out of the ordinary.

        Don’t guess running around the yard with a flyswatter is going to do any good.

  6. I found your info on the sarcophagidae fly while trying to find out what has been killing my anoles. We live in a small town just South of Houston about 30 miles and we love our green lizards because they are great insect control.
    Over the last couple of years, we have noticed lizards dying and they all have holes in them. There are several out there now with large swollen wounds that are scabbed over and they appear to be getting skinnier and poorer looking everyday.
    Your pictures match up with what we are seeing. Don’t remember anything like this in our almost 30 years here in the country, only recent years.


  7. We took in a green anole just one day ago, in New Orleans. (Actually, saved him from our cat.) The lizard did not want to go free, so we kept him in a terrarium, but then he got very weak. We took him out to hunt in some grass that’s filled with tiny grasshoppers, and then noticed movement under his skin. He died shortly thereafter, and we set him out, but it really looked like larvae crawling under his skin. Very sad, but he probably did not run from us (and wanted to stay with us) because he was sick…

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