The Chemistry of Catnip–Intoxicating & Effective Bug Repellant

Cats and catnip have a strange, age-old relationship. Catnip (Nepeta cataria) is a plant from the mint family and roughly two-thirds of catsٰٰٰ¹ are intensely attracted to this seemingly innocuous plant. Just the smell of it makes them go paw-sitively wild! They start rubbing against everything, rolling and flipping around, and even zooming around the house before it wears off within a half-hour. On the other hand, ingesting catnip seems to have the opposite effect and mellows out cats. So what gives? What kind of power does chemistry have on our feline friends?

Catnip and silver vine (Actinidia polygama), an Asian counterpart to catnip² that produces similar if not more potent effects on cats, both produce chemicals called nepetalactone and nepetalactol (respectively). These are the active chemicals that induce the characteristic behavior towards catnip. When cats smell catnip, nepetalactone enters the cat’s nose and triggers the cells in the cat’s nasal cavity to produce endorphins, the natural opioid or “feel-good” hormones. 

However, catnip and its counterparts aren’t just for pleasure. Nepetalactone and nepetalactol also act as a natural bug spray for the plants, providing protection from pests by activating insect pain receptors³. Because nature has already provided a natural bug repellent, researchers suggest that cats’ behavior to catnip is an evolutionary adaptation. 

Cats (both big and small) tend to stalk their prey in tall grass where bugs are inevitably present. When cats roll and rub against plants like catnip or silver vine, some of these chemicals become airborne and are transferred onto the cats’ fur, serving as an excellent mosquito repellant⁴. This is considered survival-related behavior because mosquitoes are carriers of a plethora of diseases (e.g., malaria, West Nile virus, Zika virus). Catnip is a purr-fect way for cats to enjoy themselves and reap the benefits of a natural bug repellant.

While brushing against the plant’s leaves is an effective way to keep bugs at bay, physical damage to the plant’s stem and leaves is even more effective. Recently, scientists in Japan have shown that physical leaf damage⁵ (e.g., from chewing) in silver vine significantly increases the amount of nepetalactol emission (by 10-fold!). The combination of rubbing and rolling with chewing leaves provides a strong pest defense compared to intact leaves. 

Now that’s what we call fun and functional for our feline friends!

These findings may be helpful for future research on bug repellents by using nepetalactone and nepetalactol to develop safer and more effective insecticides. But until then, it may be best for humans to stay away from catnip for personal use this summer…unless you want to attract the neighborhood cats!

References:

1. https://doi.org/10.1093/oxfordjournals.jhered.a107121
2. https://bmcvetres.biomedcentral.com/articles/10.1186/s12917-017-0987-6
3. https://www.cell.com/current-biology/fulltext/S0960-9822(21)00217-7
4. https://www.science.org/doi/10.1126/sciadv.abd9135
5. https://doi.org/10.1016/j.isci.2022.104455