Elongate Twig Ants (Pseudomyrmex ejectus)

Pseudomyrmex ejectus at the nest entrance (Florida, USA)

Why are Elongate Twig Ants (Pseudomyrmex species) so slender?

All the better to fit into the narrow crevices of their twiggy lodgings:

Pseudomyrmex twig ants don’t carve their own nest chambers the way most other ants do. Rather, they inhabit old burrows in twigs and stems dug by the larvae of other insects, especially beetles. Their flexible, elongate bodies allow them to maneuver in tight cavities:

Elongate twig ants comprise about 200 species found in the tropics and subtropics of the Americas. Their above-ground nesting preferences make them vulnerable to winter freezing, which is presumably why they don’t extend far into the temperate zones. That’s a real shame for we northern myrmecophiles. With the exception of a handful of hyper-aggressive ant-plant species, Pseudomyrmex are delightfully gentle, quirkly little insects.

44 thoughts on “Elongate Twig Ants (Pseudomyrmex ejectus)”

    1. I think you’ve reverse-engineered pretty much all my tricks, Ted! Yes, that’s me holding the stem a couple inches above a green leaf.

      No idea on the plant. I was too focused on the ants.

  1. I think the stem is Sambucus, Ted.
    It’s interesting how little effort these seem to have put into cleaning out the pith from this stem. In my experience, Ps. gracilis tends to do a lot of excavation and expulsion of soft material when they move into a stem.

  2. Pingback: Bichos Argentinos #2 – Pseudomyrmex sp. « Beetles In The Bush

  3. “delightfully gentle, quirkly little insects…” ok we must have a vicious sub-breed here in central Florida. The ones here sting as soon as they land on you (often, I guess they are clumsy) and the sting is incredibly painful. Painful as in it dropped me the first time and I almost called 911 – lasted 2 weeks, the entire joint hurt, and it left a hole that took another week to heal. I am not the only one to have experienced agony from just one sting! And I thought fire ants were bad…I’d rather get a half dozen fire ant stings than one of these. Make that a full dozen.

    1. Please help! I have constant stings and it’s always several. Right now I have 14 in one area. I live on an acre and must go out every day to feed my animals. What used to be my favorite place is now my hell.

    2. Shannon Douglas

      I’m with you!! NOTHING DELIGHTFUL ABOUT THEM!! Trimming trees in our backyard in Orlando. Felt like something stinging me on my neck. Then I felt stinging down my back. Next, my hands felt like they were on fire! And they started itching terribly!! I ran them under cold water and scrubbed them with a dish sponge, so hard, I scrubbed the skin off in several places!!Then MY ARMPITS STARTED ITCHING!!! I ran in the house & stripped off my clothes and jumped in the shower! When I got out, I checked my clothes and there were two twig ants inside my shirt. But, my armpits had hundreds of HUGE SWOLLEN LUMPS under them – all the way down to the inside crease of my elbows on both arms!! About a dozen dime-quarter size red welts on my neck & down my back. Rash down my chest, under my breasts all over my belly & down the insides of my legs!! I went to the Centra Care. They told me I evidently had an extremely allergic reaction to the “stings”. No kidding!! They gave me a steroid pack of Prednisone for 6 days and told me to take Benedryl – 2 every 6 hours for up to 10 days. The itching was better by the next day – the swelling went down in a few days – but it left red “blotches” on my skin for about a week. We have alot of trees in our yard – oak, magnolia, palm, camphor. So I’m freaking out about these ants being arboreal! I’ve been stung by fire ants several times over the years – NOTHING like this!!!

      1. Live in Tampa area and have been a victim of the bites of these horrible aggressive ants many times, especially this summer. I became paranoid sitting out on my deck, constantly on lookout for them. The swelling and itching are horrible and longlasting. Ice packs help. Someone said to flick them, not smack them, and that it so true. I instictively smacked one and it bit me three times in the same area. Ouch!! I may have finally found something that works. I sprayed the ground and foundation areas around my deck with Raid Max Bug Barrier about 2 weeks ago, and I have not seen them since. I didn’t expect it to work so I am amazed. This spray has an automatic trigger so it is super easy to use and aim where you want it. I hope this is a lasting solution as I do not want an encounter with one of these little terrors ever again!! Good luck to you and all the other twig ant victims!!

        1. Shannon Douglas

          Thanks for sharing! I haven’t been bitten again(Thank God!) but like you, am always “in fear” of it…………I’m getting the Raid Max Bug Barrier that you suggest – just in case I see them again. Also, have the prednisone pack & benedryl handy!!

    3. Sting can be life threatening to those who are allergic, some people have to carry an epipen to avoid shock. Swelling can last many weeks and pain is constant. Affected area can be many square inches with alarming bright red or pink swelling. A single soft wood tree can contain many nests and queens in the dead branches. All must travel the same trunk and are vulnerable to insect sprays at that point. Nests are fairly waterproof and therefore impervious to insecticides. Workers will not carry poisons to the queen. To control colonies dead branches must be removed, put in a trash can, treated with killer and placed away from the house with the lid on. Spraying will kill aphids and other nectar producing insects depriving ants of their food source. Ultimately the tree or plant may have to be cut out. ALL COMMENTS are from personal experience, I am not an entomologist but did drop the course twice.

      1. For Paul –
        Entomologist, or not, your information is appreciated. I had one of those 2-week huge swellings. I wanted to know what was needed to get rid of them. Thanks.
        Bev

    4. Elizabeth Argus

      My experience has been that these ants have powerful stings Not only that, but the pseudomyrmex in my yard (costal Louisiana) have decimated my lepidopteran population. I like to keep a pesticide-free yard, letting nature establish her own balance, but the pseudomyrmex are making it difficult to garden at all.

    1. LOL! that is probably it. Evil little things ninja-drop on me every time I pass by a tree. You know I am all for live-and-let-live philosophy but I can’t believe I found a critter I dislike more than fire ants. I believe immigration reform may need a “hominids only” clause!

  4. I live in Davie Fl, I cover from head to toe and I still get stung. My tigh and butt look lke I have a disease. My yard is my place for peace.

  5. I see that this article is about P-Myrmex “ejectus” (which I did not know about). My experience – like Robin and Judith – is with P-Myrmex gracilis and it’s pretty much the epitome of evil to me. I was stung for the first time in spring 2012 when pruning an allemanda shrub. The sting was sharp and later sent weird chills up that arm. So my body must’ve developed antibodies to its venom and when I was stung again in fall of 2012 – simply when I walked on my patio – it landed me in the hospital early a.m. the next day. Hives all over my stomach, chest, legs. They hit me with epinephrine, solumedrol and benadryl all at once – one of the worst experiences of my lives. And they’re all over my home, front and back, and I step on them every chance I get. Even when pest control annihilates them, they’re back within 1 month, all over the place. I wish I was an entomologist who could develop a poison strictly developed for them, they would be history. And Robin? Hope you keep epi-pen close at hand. You might need it one day.

  6. Pingback: Pseudomyrmex gracilis - Ameisenforum.de

  7. “they inhabit old burrows in twigs and stems dug by the larvae of other insects, especially beetles”

    **Does anyone have a source that discusses this? or even mentions it?

    I would really appreciate it, thanks!! 🙂

  8. Hello! Interesting discussion! I was trying to find out what ant stung me and what was injected to cause the welt. I discovered it was P-Myrmex gracilis and the venom had peptides in it, but that is all. It seems that ant venom is not well understood except the formic acid dispensers. I am a land manager, and I seem to get stung every time I go out in the field. People here call them “oak ants” but now I know better.

    1. Hello Alexandra. How did you discover it was the P-Myrmex gracilis that stung you? Did you have an allergy test? I had a severe reaction to a sting and I have a suspicion that it was the ‘gracilis’. I’d like to be able to firmly identify the beast that stung me.

  9. I’ve been stung by them several times. While I’ve never had the reaction that you folks had, they are quite painful. To me it’s like a bee sting, but not quite as intense.

  10. Bev H
    This afternoon, while doing an outdoor event as a volunteer, I felt something on my forearm. As soon as I saw it was a twig ant, I pinched it and killed it. It was too late. One bite was enough.
    Here in central Florida I have been bitten by them a number of times over the past 20 years. The first time, on my neck, I was sure it was a wasp. Each time I have gotten a hard, hot welt that expands to a 2-inch diameter. This is the worst, and I wonder if it is because that hand is recovering from 20 fireant bites a week ago. I use StingStop topically and take homeopathic Apis and/or Ledum. The fire and pain goes down, but the welt takes awhile. They do not get the pustule that fireant bites do. NOT a “delightfully gentle” beast . . . and I loved my entomology course as a biology major!

    1. A photo on another site showed a wasp-like stinger on the abdomen – so definitely a sting, not a bite. Like velvet ants – are they a wasp?

  11. I want to know what common insecticide will kill these twig ants. Regular ant spray of any brand does not affect them. They just keep on going. The only thing I know to kill them is ant and hornet spray, but I don’t want to use so much to kill one ant at a time.

  12. About 2 years ago I was stung by one of these ants while carrying yard debris. I swatted it off me but it was too late. The pain was horrible – much worse than fire ants or wasps or bees. I started having a reaction and my lips and tongue were swelling and my palms were itching uncontrollably. My husband took me to the walk in clinic and they gave me the epi medicine and called an ambulance. I finally got home hours later after much medication. It cost me several thousand dollars for that horrible ant bite. Now I carry an epi pen. Have been stung by bees and wasps before with normal reactions to those. That ant bite was extremely painful and I will do anything to avoid that pain again. Can’t describe it but it’s severely painful. Never again.

    1. Shannon Douglas

      Same here!! I was stung/bitten about a year back. PAIN WAY WORSE than fire ants, bees or wasps!!! I’m in Orlando. My husband & I were doing yard work in the backyard – about an acre. He had trimmed several palm fronds. I loaded them into cans & hauled them out to the road. I thought I felt something stinging the back of my neck. My husband looked, but said he didn’t see anything. All of a sudden, my palms started to itch uncontrollably!! I went into the house & SCRUBBED them with a scrub daddy sponge until they were almost bleeding! My neck was still stinging and now BOTH ARMPITS were itching and on fire! I ran inside, stripped off my clothes and jumped in the shower. When I got out, I told my husband I was driving to the Centra Care Clinic. I saw a couple of ants on the t-shirt I had been wearing. I put the ants in a ziplock bag & took them with me. By that time, I had a rash all over my chest, my belly and down the insides if both legs all the way to my knees!! I also now had huge red welts down the insides of both arms – from the elbows to the armpits & down my sides to my waist!!! Got to Centra Care – which of course was closed – this being Sunday afternoon…. Drove to Walgreen’s, hoping their minute clinic was open – Nope, closed, too! But the pharmacist told me to take the highest dose of Benydryl & that I probably needed a Steroid (Prednisone) pack. I debated going to the Emergency room, but remembering the last trip there being over a 4 hour wait – I drove home, took the Benydryl & Prednisone (from my dog’s allergy RX) and about 1 hour later everything started to subside. By two hours, swelling, itching & rash were almost gone. Still had scraped hands and red bite marks, but felt ALOT BETTER. Went to the clinic early the next day, Dr. said I had an allergic reaction to the ant bites – NO KIDDING!!! He did prescribe the Prednisone pack. I took the ants to the AG Center. They told me they were Elongated Twig Ants. They did say, they usually bite when they get trapped in your clothing. Later that night, my husband told me he had seen the ants in the palm fronds – even had some fall on him – but, he just brushed them off & didn’t get bitten. (I thanked him for warning me about them at the time……) Anyway, in conclusion, I’d rather have another HYSTERECTOMY than get bitten by these ants again!!!

      1. No one mentioned carrying an epi pen? With that kind of reaction, I would have expected someone to have said something. I wouldn’t wait, if I were you, if there is a next time – and I hope there isn’t. That was a nasty reaction! (I kill every one of those critters I see! I get a huge welt with every bite, but no body reaction – yet.)

        1. Shannon Douglas

          Thanks, Bev.
          Used to carry an epi pen a few years back, since I was getting weekly allergy shots (for weeds, mold, etc>) and the allergist required I have one when I came in for the injections. But, if I remember correctly, seems like it was about a $250 copay for one even with insurance. Then the expiration date rolled over…..and the allergy shots really weren’t doing any good….so I stopped the shots and never got another epi…
          But, maybe the prices have come down. I’ll check on it. Really never had any shortness of breath issues with the ant bites, though…just the pain & welts & itching. Yep, I’ll kill ‘um, too! But, luckily, haven’t had another bite. I do worry about my dog getting bitten, too. She’s a hunting dog (even though, we don’t hunt) and she always has her nose to the ground digging at something. I’m afraid if she digs in any debris, she’ll get bitten, too. And since she already has Steroid Responsive Meningitis which compromises her immune system, I’m afraid she’d be dead if she got stung. She’s been on prednisone her whole life – 9 years. So maybe the steroids in her system would help, but she just can’t fight anything off. Was just in the Specialty Veterinary clinic for a week with round the clock oxygen and antibiotics…$$$$………Sorry, another story……..

  13. This species (Pseudomyrmex gracilis) is actually pretty interesting. I have been wanting to found a newly mated queen of that species for quite awhile now. I have a heavy interest in Myrmecology, and currently have a 7 month old Camponotus floridanus (Florida Carpenter Ant, caught the queen this past June 2019) colony. Twig ants do indeed pack one hell of a sting for sure. I have been stung by them twice and broke out it small rashes/welts. I would certainly take Fire Ant stings any day over the Twig Ants. They are usually not an aggressive species unless the nest is disturbed or if they happen to fall on you and get caught within your clothing. They have relatively small colonies usually 35-50 workers tops, while Fire Ants number in the several thousands. Pseudomyrmex gracilis originally was not a native species to Florida, but has become established here in the US for quite a long time now (native species now). Some might call me crazy for wanting to rear a colony of the Twig Ant lol, but I would risk it just for personal study and research.

    1. Shannon Douglas

      Yep, you can have ALL of mine, too – here in Florida… Do I think you’re crazy for wanting to breed a colony of them? Yes! Of course, if you want to study them to figure out how to ERADICATE them, I’m all for it! If you’re planning on breeding them to use as a “Weapon of Mass Destruction”, you’re probably on to something…..

      1. Elizabeth C Argus

        I seriously need help eradicating them from my yard … Without the use of insecticides. I have looked up ant-eating birds. I have lots of chickadees, who occasionally eat ants. I don’t know if they can tackle these Pseudomyrmex. Any known predators, or other natural means of control … Without insecticides. ???

      2. I can definitely understand the frustration that many have with the Twig Ants. They do possess a stinger at the end of there abdomen which causes moderate to severe pain. But they are not an aggressive species like the invasive Solenopsis invicta (Red Imported Fire Ant). Twigs ants will actually avoid us due to there exceptional eye sight. But if they happen to fall on us from the trees or if anything disturbs there nest accidently/aggressively they will become defensive. A good aspect about them is that they do hunt other insects that are destructive to plants and crops. In my honest opinion, Fire Ants are far more dangerous to us, and they have been documented in causing a lot of human deaths. My reason for wanting to found a colony of Twig Ants is to study there social behavior, growth of brood, hunting behavior, and lifespan within captivity. (No intentions for weapons of mass destruction lmao). As to eradicating them when you have too, probably standard bug spray, and hair spray which usually freezes/kills insects in their tracks. But as with any species of ant, you have to kill the queen/nest in order to truly get rid of them. From what I understand hearing from keepers of Twig Ants, their nests can be very hard to locate. And I’m not 100% sure, but natural predators to Twig Ants might be smaller species of ants like Fire Ants, or Big Headed Ants. I would imagine that birds or lizards etc being larger targets are prone to the Twig Ants sting.

        1. Elizabeth C Argus

          I am sympathetic to your thoughts. Pseudomyrmex are, in isolation, beautiful creatures. In my yard, however, they have decimated my lepidopteran population. I don’t consider native invertebrate life “pests.” In fact, since the Pseudomyrmex have moved in, my yard has become a quiet, sterile, boring place. I lament this loss. (And then there are the stings I sustain when I’m working in the yard, which we have covered.) I agree, fire ants are a scourge, but comparing Pseudomyrmex to fire ants is a red herring. I repeat, if you want to come find my queen(s), you are welcome! 🤠 Peace!

  14. Hi everyone
    Very interesting reads about the twig ant. I live in Navarre FL, panhandle area. These ants are always on my concrete patio and patio furniture. Only on the patio with the awning, no where else around the pool deck. I have grass and rocks around my deck. Bushes and crepe myrtle are about 10 feet away. I am guessing they are living in the mulch around them. Though when I do the gardening I dont see them.

    Anyways started to investigate these darn ants since my husband has been stung by them here recently. Not me yet, but knock on wood. Trying to find an effective way to get rid of them. I do have the house sprayed quarterly but that doesnt stop them from climbing the walls. I have even sprayed the patio furniture with bug spray. Any help would be appreciated.

    Stay safe !

    1. Hi, we have also been battling these ants near our patio and it seems they will travel decently far, the main shrub they are living in is 8-10 feet from the patio. However, pay attention if you have patio furniture made of wood. I discovered the ants were actually creating holes and living in my patio table and bench! My solution was to restain the table, which worked to keep them away about a year. Then they moved back in so I’ve painted it which I think will be less inviting to gnaw through. Fingers crossed. I was so surprised they did this, as most articles about them say they live in already hollowed twigs.

      Good luck!

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