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.

29 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.

    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.

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