In UK homes, dogs most often encounter ants, cockroaches, bed bugs, fleas, various small beetles and moths, plus silverfish, woodlice and houseflies. For most healthy dogs, a single, tiny, non-stinging insect swallowed by accident is unlikely to cause more than transient tummy upset, but several household pests carry clearer risks.

Cockroaches are the primary indoor hygiene concern. They’re recognised public-health pests that mechanically spread food-poisoning organisms on their bodies and in their droppings; any dog that scavenges near a roach problem is more likely to come into contact with bacteria that upset the gut. The priority is prompt control and strict kitchen hygiene; keep pets away from baited areas during treatment.

Bed bugs are a nuisance more than a toxic hazard to dogs. They don’t transmit disease, but bites can cause itch and secondary skin infection from scratching; pets can also “hitchhike” them around the home in collars or bedding. Focus on eradication and managing any skin irritation rather than worrying about poisoning from ingestion.

Fleas are different: if a dog swallows an infected flea while grooming, it can acquire the tapeworm Dipylidium caninum. This is a common UK route of tapeworm infection, so effective flea control and routine worming matter if your dog is chewing and ingesting fleas.

With silverfish and woodlice, the issue is usually damp, not toxins. Silverfish are considered harmless to people and pets but indicate humidity problems; woodlice are similarly harmless indoors and signal moisture that needs fixing. Address the underlying damp and keep food and waste sealed to reduce sightings.

A single housefly swallowed indoors rarely matters, but flies can still contaminate surfaces and, more importantly, lay eggs in soiled fur or wounds, leading to myiasis (“fly-strike”), which is a veterinary emergency. Keep bins closed, maintain coat hygiene, and seek urgent help for any wound that looks “fly-struck.” 

Outdoors, dogs meet a broader range of species and hazards. Bees and wasps can sting the lips or mouth; local swelling is common, and while allergic reactions are uncommon, they require prompt veterinary care. Spiders are generally of low medical significance in the UK, but the noble false widow can cause painful bites; severe outcomes are rare, and the main risk is a defensive bite rather than toxicity from swallowing one.

Seasonally, oak processionary moth (OPM) caterpillars are a noteworthy risk in parts of England. Their urticating hairs can irritate the skin, eyes and airways of people and pets; the public health advice is to avoid contact entirely and report sightings during the high-risk period (typically May–July). Seek veterinary advice immediately if exposure is suspected.

Slugs and snails are a different concern: they can carry the lungworm Angiostrongylus vasorum. Dogs become infected by eating slugs/snails (or sometimes from contaminated grass, toys or water), and lungworm can be fatal without treatment. Prevent access, refresh outdoor water bowls frequently, and ask your vet about preventive deworming that covers lungworm.

Most outdoor beetles and moths are more of a nuisance than a toxin risk, but avoid encouraging deliberate “bug snacking”: you can’t know what a wild insect has contacted (e.g., pesticides), and some caterpillars carry irritant hairs.

As for ants, UK garden species usually cause brief oral irritation at worst; painful fire-ant style stings aren’t established here, so reactions tend to be local unless your dog is allergic.

For flies in warm months, the same myiasis warning applies to soiled fur or wounds: keep coats clean and check them quickly after muddy or wet walks.

If you catch your dog eating a bug, try to remain calm. First, remove any visible stinger or insect parts from the mouth using tweezers or a damp cloth. Rinse the mouth gently with water to help reduce irritation. Avoid inducing vomiting unless specifically advised by your vet: in some cases, this can worsen irritation or risk aspiration.

Watch your dog closely for signs of discomfort, swelling, or distress. If symptoms develop, take a photo or sample of the insect if possible; this can help your vet identify potential toxins. For mild cases, your vet may recommend an antihistamine or a bland diet for a day or two. For more severe reactions, immediate veterinary treatment, such as anti-inflammatory medication or IV fluids, may be needed.

Prompt action is key. Even small insects can cause significant problems for dogs with allergies or sensitivities. The sooner you seek advice, the better the outcome is likely to be.

Prevention starts with awareness. Dogs that spend a lot of time outdoors are naturally more exposed to insects, especially in warmer months. Keeping your garden tidy, clearing fallen fruit, trimming overgrown plants, and removing stagnant water helps reduce insect populations. You can also discourage bugs by securing bins and promptly cleaning up pet waste.

During walks, supervise your dog when they’re sniffing around flowers, compost heaps, or hedgerows where wasps, bees, and spiders are common. Training a solid “leave it” command can be invaluable, especially for curious dogs that like to chase anything that moves.

Always use pet-safe insect repellents if needed and avoid applying human-grade bug sprays near your dog’s face or coat. And while insect-based dog foods and treats are increasingly popular, only buy from reputable brands that meet UK pet food manufacturing standards.

Dogs are naturally inclined to chase and sometimes eat insects, but not all bugs are harmless. While a single fly or cricket may not cause concern, repeated exposure or ingestion of venomous or contaminated insects can lead to serious health issues. Always monitor your dog after insect encounters and don’t hesitate to contact your vet if symptoms appear.

As a rule, prevention is far better than cure. Keep outdoor spaces clean, supervise curious pups, and teach clear commands to stop unwanted snacking. If you’re interested in exploring insect-based nutrition safely, look for products designed for dogs rather than relying on what’s crawling in your garden.

For more expert-led guidance, explore our Can Dogs Eat series to learn how to keep your dog’s diet safe and balanced.