Ants in your house or yard: October 2011 Archives

Dear AntAsk,
My name is Hadar and I live in Israel. I am the owner of the company for pest control in Israel that specializes in the extermination of ants using baits
During the last five years we are dealing with the failure of eradication of the species Plagiolepis. We've tried most types of bait offered the U.S. pesticide market without success. Needless to say that spraying pesticides is not effective at all.
We tried various baits containing borax or fipronil or abamectin B1 imidiachloropid.
The baits contain honey dew or protein. Often appears in the attraction of that work and "workers" vigorously and after a while sometimes minutes, sometimes days after the placement of abandoned ant bait
Can I get some information about the lifestyles of this ant? Such as:
What kind of diet prefers this species?
Is there more than one queen in the nest?
How to deal with this pest
This species is very common throughout the country from north to south
Unfortunately, an Israeli research on this species is not done yet
Please help

Dear Hadar,

Sorry to hear that you're having trouble with Plagiolepis. Although only a few species have been studied in depth, it seems that there is evidence of polygyny (multiple queens in the same colony) in every species in which this quality has been looked for ( P. pygmaea, P. xene, P. taurica, P. schmitzii, and P. maura - data and references in Thurin et al. 2011; DOI: 10.1111/j.1365-294X.2011.05161.x).

As for what your Plagiolepis eats in the wild, it is likely that even if we did know what species you were working with, there would not be a complete, published study that would answer this question. What is more important is that you continue to experiment with baits to which this ant might be attracted that you can mix with the appropriate poisons. Invasive ant expert Cas Vanderwoude ( explains:

We have Plagiolepis alluaudi here in Hawai`i. They seem fairly "skittish" and do not seem to feed on any particular food source. I think they are present in homes more for water than anything else.

My standard approach would be to offer a buffet of food items that they might feed on, add a toxicant to the most attractive item and bait with that mixture. So Hadar, try a little (1)peanut butter, (2) jam or jelly, and (3) spam or tuna or fish flavored cat food. Also, try water. Put it in a vial filled with cotton wadding so the ants can "suck" the water from the wadding. You might be surprised - it might be water they recruit to most! If that's the case, thank my friend Evan Harris for that suggestion... if water and sugar are both attractive, you can make a nice attractant out of sugar water (25% sugar) and place it in the vials mentioned previously.

Adding a toxicant is the next step. If you have fipronil it will be the most effective. The most important thing is the dose. DO NOT OVER-DOSE!!! For fipronil, use only 0.1g/kg bait mix - NO MORE! The effective range will be 0.01-0.1 g/kg active ingredient. Any more and it will take effect too soon and leave the queen(s) unaffected. Repeat baiting every 6-8 weeks."

In addition to Cas's tips, I would add that it is important to apply poison at an effective spatial scale. If you're going to poison the ants in one person's house, but they live two meters away from a large colony, there is a very strong likelihood of re-infestation. Cas's point about re-applying baits is also very important; no treatment will kill 100% the first time. Often, treatments will kill around 90% of the ants at most, so it is important to keep re-applying the pesticide at the right time intervals. Ants do not eat while they are in their pupal stage (something like the cocoon a caterpillar makes before becoming a butterfly), so re-applying pesticides while the same ants are in their pupal stages will not increase the effectiveness of the treatment.

For further information about dealing with invasive ants, I'd encourage you to check out Cas's website (above). For example, there is some information on treating potted plants for pests by submerging them in water at 45C which might be useful for some situations.

I hope this helps!
Jesse Czekanski-Moir, Cas Vanderwoude, and the AntAsk Team


I would like to know if there is any sense to make out of the strange behavior I witnessed an ant making in my house.

I live in Long Island, NY and I guess the type of ant was a regular black carpenter ant. The first thing that struck me odd was that it had a very narrow thorax, almost like it was pinched in...But that might be 100% normal and I've just never looked that hard at an ant before.

The second thing that struck me odd was that it was standing still and seemed to be jittering its legs while they were planted on the floor, almost like wobbling them. I thought maybe it was neurological damage? Poison? I don't know.

I decided to get some cookie crumbs and a plastic cup so I can try to feed it and observe it for a little while. It did eat a bit which made me feel better. The next strange behavior I saw was that it started grooming the hell out of itself, almost manically as if it was on speed, then it proceed to bite at the bottom tip of it's abdomen. It was freaky; I thought maybe it was pregnant and ready to pop out some eggs or something. I don't think it was, though. It was really weird. I hope he wasn't sick or poisoned. I named him Mercury. I got grossed out from lying on the kitchen floor to watch all this and let it go off into the sunset...


Cheryl Cusimano


Hi Cheryl,

The ant you found was very likely a carpenter ant, but without a more thorough description or any photographic cues, this might be hard to confirm. The "narrow thorax" you observed could have been either the petiole of an ant (the small segment joining the mesosoma and gaster that gives all ants and many other hymenopterans the appearance of having a "waist") or the constricted petiolar segment of a parasitoid wasp. Ensign wasps (family Evaniidae), for example, superficially resemble black carpenter ants and are familiar (if less common) interlopers in domestic settings given their predatory association with cockroaches.

The jittering movement is likewise difficult to explain without further observation. If the insect was indeed an ensign wasp, you might compare this behavior with descriptions of the wasp's peculiar bobbing movements, which involve jerking its abdomen up and down like a hatchet.

The meticulous grooming behavior you observed is characteristic of almost all insects, especially after a meal. Whether this particular individual was an ant or a wasp, obsessive self-grooming would not be unexpected following close inspection of foreign objects like cookie crumbs or plastic cups.

Hope this helps,

Alexandra Westrich & the AntAsk Team

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