Are unusual ants around Castro Valley home cause for concern?

DEAR JOAN: Can you help me identify this new type of ant I’ve been seeing on my property lately? They have red middles with black heads and bottoms. They have little piles of dirt around holes in the field where they live.

I’ve noticed that they’re very active at night.

Rob, Castro Valley

DEAR ROB: Your new neighbors are carpenter ants. There are two types — one is all black, while the other is red and black — and we have both in the Bay Area.

While all ants, it seems, are industrial, the carpenter ants take it to extremes and are quite active at night.

Carpenter ants, unlike termites, don’t eat the wood, they just bore holes in it and dig in to make nests. Although you are seeing ground nests, there likely is a central hub for them nearby in a tree or stump. There’s a good chance they could eventually make it to your home.

The ants usually start in an area that already is weakened from water damage or wood decay. They begin tunneling in, creating an extensive network of galleries and working their way into more sound wood. They also can and will create nests in wall voids, hollow doors and insulation.

If land is cleared where they have an established colony, that can cause them to move into surrounding buildings, including into new construction.

That doesn’t mean they are bad insects. They actually do a wonderful job of clearing away rotting wood and dead trees.

To help prevent them from going into places we don’t want them, experts recommend:

  • Trimming tree branches and shrubs away from structures to prevent access
  • Sealing off potential entry points such as where utility lines enter a structure
  • Reducing mulch around buildings to discourage nesting
  • Replacing decayed or damaged wood and fixing problems that cause decay including clogged rain gutters and leaky pipes
  • Increasing ventilation to damp areas including the attic or subfloor spaces.
  • Reducing the number of aphids on plants — the honeydew the aphids produce can attract ants of all sorts.

DEAR JOAN: When we moved here about 10 years ago, we attracted a scrub-jay to our patio table by first placing unsalted peanuts on the patio, moving the peanuts closer to where we were sitting and eventually to the patio table itself. This has continued with various jays and now there are three.

They have trained us well. If there are no peanuts on the table in the morning, a jay looks into our kitchen window until we put some out.

This week we saw a jay attacking and eating a small bird at the squirrel-proof seed feeder. We had not seen this before. Occasional hawks yes, but not jays. We have responded by not providing peanuts with the hope the jays will go away with time.

Is this normal scrub-jay behavior or do we have an overly aggressive bird?

Paul and Carol, Pleasanton

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