My sister has an infestation of winged insects eating through the cinderblocks of her basement. Needless to say, this is terrifying. What are they and how do you control them?

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These insects bored about 20 holes though cinder block and about 5 holes through the mortar. the holes were about 3/16" in the center, and about 1/2 inch at the opening (creating a funnel shaped opening). Will post more pictures tomorrow.


3 Answers 3


Insects are incapable of "eating" concrete, but they do tend to exploit weak or damaged concrete to access something more appealing, such as a food source or nesting site.

It only takes a small crack in an otherwise secure concrete foundation to let termites in. Poured concrete is the most reliable, but if you have a block foundation, the mortar is likely to provide open spaces. Expansion joints between home sections are another invitation to pests, as is any area where pipes or wires enter the house.

Once inside, termites build dirt tunnels. These tunnels get wider over time, so even though the bugs aren’t eating your foundation, they can cause a great deal of damage as pressure builds up and widens existing cracks. This slow process may go unnoticed until it becomes serious, making regular inspection of your home and foundation an important part of pest control.


Eradication is best left to a professional for something this serious.

  • 1
    I am the professional. I have been collecting and identifying insects since I was a child and I still do; and I happen to make pesticides for a living... but still, this was a first for me (if I had not seen it with my own eyes, I wouldn't believe it either). So I thought that it would be something worth sharing. Jul 18, 2016 at 13:45

I believe that they are pavement ants (Tetramorium caespitum)... but I can't be certain. Boring holes in concrete does not seem to be one of the characteristics of this insect, aside from a few colloquial reports.

At any rate, sevin-liquid (aka carbaryl or 1-naphthyl methylcarbamate) works. Using a syringe to fill the holes that they bored seems to have worked.

Also, borax should be applied for long term control, and the holes should be filled.


Boring holes through cinder blocks sounds like Formosa Termites. They live in the Louisiana area which matches the climate of Southeast Asia. After WW II, many items were shipped back from Southeast Asia to the US in crates made from local wood. Some of that wood was infested. Back in the US the crates ended up in the landfill and the termites thrived in the climate. Formosa termites are a serious problem and can render a house unlivable in as little as 2 years.


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