Sunday, May 26, 2013

Ant Control

The spring indoor migration has begun. Argentine ants, those busy little black ants, are march, march, marching through the kitchen and bathroom.
In years past, we would reach for the spray can and douse those little scavengers. But not anymore.
 Many of those indoor spray pesticides are only effective with direct contact on the ants. And the stronger sprays, with residual action to thwart the next wave of ants, is potentially harmful to you, your kids, your pets.

So, here is what we are doing in 2010: following the recommendations of the UC Davis Integrated Pest Management Project for Ant Control.
That includes:
• Determine what the ants are attracted to and remove the food source
• Vacuum trails, wipe them with soapy water, or spray with window cleaner
• Locate entry points and caulk openings or plug with petroleum jelly
• Put out bait stations or apply gel bait at entry points
• Baits take time to work so continue to clean up trails
• Indoor sprays are not usually necessary.
• Avoid products packaged as granules that contain the active ingredients cyfluthrin or permethrin. Although these products may be mistaken for baits, they are actually contact insecticides that rapidly kill foragers and do not control the colony.

Before wiping up (or wiping out) the little critters, follow their trail. Note their entry point into the house. Seal it up. We have found ants entering the house in a variety of small avenues: beneath moulding, cracks in the window frame, behind electrical outlet plates...and one of the ants' favorite entries: that large holes beneath the sink where the pipes enter the house.

According to the UCD IPM page on ant control, "If ants can be thoroughly washed away and excluded from an area, an insecticide is probably not necessary. Vacuuming up ant trails or sponging or mopping them with soapy water may be as effective as an insecticide spray in temporarily removing foraging ants in a building because it removes the ant’s scent trail, especially if thorough cleaning is done at the entry points. Some soap products such as window cleaners can kill ants on contact but leave no residual toxicity. Certain plant-based oils are also applied for this purpose, but their odor can be offensive."

Oh, and another lesson we learned the hard way: if you put those ant baits indoors, you will attract more ants inside. Look for ants crawling along the outside of the house, and place the baits there, being sure to follow all label directions.

What about those ant sprays that are intended to be used as a perimeter spray along the outside of the house? Stick with the bait traps, says the UCD IPM page: "Spraying around the foundation will not provide long-term control because it kills only foraging ants without killing the colony. Perimeter treatments may appear to knock down the population, but ants will quickly build back up and invade again. To try to achieve long-term control, some pest control companies offer monthly perimeter spray programs. Perimeter treatments pose more risk of environmental upset than baits in bait stations and are less effective than a bait-based IPM program."

Ant baits are not ant traps, even though it may look like they are stuck there. The whole point of ant baits: they get the stuff on them, take it back to their nest, where they share it with others...and then croak. Be patient. It may take a week or so for the baits to work on the ant nest.

More info about ant baits from the UCD IPM project: "Baits are insecticides mixed with materials that attract worker ants looking for food. They are a key tool for managing ants and the only type of insecticide recommended in most situations.  Ants are attracted to the bait and recruit other workers to it. Workers carry small portions of the bait back to the nest where it is transferred mouth-to-mouth to other workers, larvae, and queens and other reproductive forms to kill the entire colony. Bait products must be slow-acting so that the foraging ants have time to make their way back to the nest and feed other members of the colony before they are killed. When properly used, baits are more effective and safer than sprays.

• Sweet sugar baits such as boric acid (use low concentrations with less than 1% of the active ingredient) are highly attractive to Argentine ants throughout the year.

• Protein baits are attractive to ants in spring when colonies are producing new offspring. (Baits like fipronil or hydramethylnon are effective.)

• Place baits in late spring or early summer when populations are low.

• Place baits outdoors; avoid indoor baiting as that may attract more ants into the home.

• Place baits near nests, trails, or along foundations.

• Baits should be placed in protected areas away from children and pets.

• Offer small portions of each bait to see which one is preferred before employing an extensive baiting program.

• Follow up regularly to make sure bait is working and place fresh bait as necessary.

How baits work:
• Worker ants are attracted to the bait and take it back to the nest where the entire colony, including queens, may be killed.

• Bait must be slow-acting so workers won't be killed before they get back to the nest.

• Results may not be evident for several weeks.

• Bait stations or ant stakes are easiest to use and safest for the environment."

Ant baits contain various active ingredients and attractants. We have tried a variety of different ones, to appease the finickiest of ant diners. One of my favorites is one that uses boric acid, a less toxic alternative.

But again, use it outdoors...otherwise, you will be drawing more ants inside.


  1. Hi Fred, ants hate Diatomaceous earth they wont cross a line of it and when it's put on their hill they leave. I use a quart plastic container with a screw on top that has small holes punched in it (I use a dart to make em) like a salt shaker 2/3rds full of DE and when you see a bad guy or ant just dust em. The dust is minimal, avoid breathing the dust just like any garden product. DE is a good source of silica too. Keep it up you look good. Ken

  2. You are absolutely right, if we put those ant baits indoors, we will attract more ants inside. We should use those baits in such a place which will not invite ants inside our house. Thanks Fred for your nice article.