Insects That Pets Shouldn’t Eat

Laurie Anne Walden, DVM

Some bugs carry dangerous diseases or have venomous stings. But what about insects that our pets catch and swallow? Most are harmless, but a few are unsafe for pets. As warm weather arrives, keep an eye out for insects that can cause trouble if they’re eaten.
 
Pesticides and insecticides can also be toxic to pets. Keep these products out of your pets’ reach and use them only according to the manufacturer’s instructions. Dogs and cats are most likely to get a toxic dose if they’re sprayed with the product or eat a significant amount. A pet that eats a single pesticide-covered insect would ingest a little bit of the product, but the amount would probably be too small to cause a problem (call your veterinarian if you’re unsure or if your pet shows any symptoms).
 
Caterpillars
Caterpillar hairs can be irritating to the touch, and some types of hairs release a toxin. Fur typically protects dogs’ and cats’ skin from the stings of caterpillar hairs. If a pet eats a caterpillar, though, the hairs can irritate the mouth and throat. Symptoms include drooling, pawing at the mouth, shaking the head, vomiting, and trouble swallowing. Processionary caterpillars (found in Europe, North Africa, and Asia) produce a toxin that causes an especially severe reaction.[1,2]
 
Fireflies
Fireflies are highly toxic to lizards, amphibians, and birds. Ingestion of a single firefly can kill a bearded dragon. Fireflies contain lucibufagins, which are chemicals that cause heart damage in susceptible species.[3]
 
Asian Lady Beetles
Asian lady beetles (Harmonia axyridis) look a lot like ladybugs, but unlike ladybugs they gather in large numbers and come inside houses in cold weather. As a defense mechanism, they secrete an irritating chemical compound. One published report describes a dog with oral trauma similar to chemical burns caused by 16 Asian lady beetles stuck to the roof of the mouth.[4]
 
Blister Beetles
Blister beetles (family Meloidae) produce a toxin called cantharidin, an irritant that causes blistering on contact with the skin, mouth, or digestive tract. Cantharidin poisoning is most common in horses that eat alfalfa hay contaminated with blister beetles. Exposure can be fatal to horses. Other species, including dogs, cats, rabbits, and people, are also susceptible to cantharidin poisoning.[5]
 
Walking Sticks
The insects known as walking sticks (order Phasmatodea) use camouflage as their main defense mechanism, but some of them also secrete a chemical that can burn the eyes or mouth. Anisomorpha buprestoides, a stick insect found in the southern United States, can aim this secretion directly at the face of a predator. Severe eye damage has been reported in humans and a dog.[6]
 
Bombardier Beetles
Brachinus beetles are called bombardier beetles because they secrete a toxic chemical that they aim at predators in what is usually described as “explosive discharge.” This chemical irritant is released at a boiling temperature.[7] Although I did not find any research reports of bombardier beetle poisoning in dogs or cats, I can’t imagine that eating one would be a comfortable experience.
 
References
1. Bad bugs, bad bugs: what you should do to keep your pets safe. ASPCA. August 1, 2018. Accessed March 5, 2021. https://www.aspca.org/news/bad-bugs-bad-bugs-what-you-should-do-keep-your-pets-safe
2. Fuzzy green poisoners: caterpillar toxicosis in pets. ASPCA Pro. Accessed March 5, 2021. https://www.aspcapro.org/resource/fuzzy-green-poisoners-caterpillar-toxicosis-pets
3. Treating firefly toxicosis in lizards. ASPCA Pro. Accessed March 5, 2021. https://www.aspcapro.org/resource/treating-firefly-toxicosis-lizards
4. Stocks IC, Lindsey DE. Acute corrosion of the oral mucosa in a dog due to ingestion of multicolored Asian lady beetles (Harmonia axyridis: Coccinellidae). Toxicon. 2008;52(2):389-391. doi:10.1016/j.toxicon.2008.05.010
5. Schmitz DG. Overview of cantharidin poisoning. Merck Veterinary Manual. Updated June 2013. Accessed March 5, 2021. https://www.merckvetmanual.com/toxicology/cantharidin-poisoning/overview-of-cantharidin-poisoning
6. Thomas MC. Featured creatures: twostriped walkingstick. University of Florida Entomology & Nematology. Publication No. EENY-314. November 2003. Accessed March 5, 2021. http://entnemdept.ufl.edu/creatures/misc/walkingstick.htm
7. Schaller JC, Davidowitz G, Papaj DR, Smith RL, Carrière Y, Moore W. Molecular phylogeny, ecology and multispecies aggregation behaviour of bombardier beetles in Arizona. PLoS One. 2018;13(10):e0205192. doi:10.1371/journal.pone.0205192
 
Photo by Kazuky Akayashi

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