Insecticide use always carries some risk, even if it's a lower risk for some chemicals over others. While the EPA does evaluate pesticide impacts on organisms like birds, fish, and other animals, those impacts might not be equal from one species of bird/fish/etc. to another. Birds do eat ants, as do a range of other animals (like amphibians, which can be very pesticide-sensitive because of their absorbent skin).

Are the ants nesting in the home? If not, a perimeter spray should not be needed, and if they are, treatment of the nest site or use of ant bait stations should be all that's needed, since a perimeter spray would not have long-lasting impacts. Carpenter ants tend to preferentially excavate wood that was previously damaged by water, like from pipe leaks, window frame leaks, etc. Other ant species won't necessarily chew-out tunnels in wood, and might nest in wall voids, which is why identification of the ants in question by a professional can help determine what action to take. If ants are only entering the home to forage and are nesting outside, the only intervention needed is to seal-up any access points to keep them from getting inside, like looking for gaps/cracks and worn-down door/window weather-stripping.

If the spray is performed anyway, to be cautious, empty the bird baths and don't refill them until the spray residues have dried. (This is more to discourage birds from entering the treated area too soon, since pyrethrins are reported to have low toxicity to birds, and they break down fairly quickly in water when exposed to sunlight.) Sprays of this nature are usually using an active ingredient(s) in the pyrethroid chemical class, and these are synthetic and longer-lasting versions of the organic ingredient pyrethrin, all of which are non-selective chemicals, capable of impacting any insect that comes into contact with its residues. Being organic, pyrethrin will degrade / break down faster in the environment than pyrethroids will. The National Pesticide Information Center, which is linked above, also contains some fact sheets about a few pyrethroid ingredients.

Miri

Thank you so much for this advice and guidance! The ants aren’t really coming into the house much, just occasionally to scout so we will leave that be. I don’t want to harm anything and it’s good to know that perimeter sprays don’t do much anyway.

Hello Holly,

Most insects indoors are merely a nuisance and not a health risk, and they enter by means of access points like gaps/cracks in exterior walls, around vent covers or pipe entry points, worn-down door weather-stripping, and so on. Sealing what access points you can will help to reduce how many insects make it inside, and keeping outdoor lighting off (like on a porch) can also discourage insects from lingering on or close to the house, since many night-active insects can be attracted to sources of light. They can more easily get inside, even if by accident, when doors are opened if they are loitering outside by a porch light.

Silverfish tend to feed on sources of starch like book bindings or wallpaper paste. More information, including management/prevention tips, can be found on the linked pages.

Centipedes are predators, eating insects (including silverfish), spiders, and other arthropods, so in that regard, they are beneficial, even if a nuisance. They wander inside by accident as they explore, and may be drawn to dark or damp areas, at least during summer. More information, including management/prevention tips, can be found on the linked pages.

Spiders are also predators, feeding on insects and occasionally each other. Some can live indoors their entire lives, while others wind-up inside by accident. Some build webs, while others wander around to find prey instead. The same management approaches to discouraging silverfish and other household insects will also keep spider populations at a minimum.

The primary function of diatomaceous earth (DE) is to suppress insect and arthropod pests through direct contact with the powder. DE absorbs oils and waxes from insect exoskeletons, causing dehydration and death. These particles with microscopically sharp edges also abrade the exoskeleton, accelerating dehydration. It must remain dry to function; once wet, it will not work. Amorphous DE, which may be labeled as “natural grade” or “food grade,” is the form used as a pesticide. Make sure the product is labeled for pests (and in this case, also for indoor use) and has an EPA registration number. Do not substitute pool filter-grade (crystalline DE) as it is very dangerous if inhaled and it does not effectively dehydrate pests. If misapplied, the dust may irritate lungs, skin, and eyes, but if label directions are followed, it should be fine to use. The National Pesticide Information Center has a fact sheet on DE if you're interested (see link).

Miri