Ecology and life cycle
Protecting yourself
The key thing you can do is to avoid deer ticks (only deer ticks can pass on Lyme disease). People who stay inside all day watching Jeopardy re-runs are very unlikely to get Lyme, as we’ve discovered during COVID lockdowns. However, this is bad for your health in other ways and is not recommended. At least change the channel now and again. When you’re outside, try to avoid areas where ticks like to wait for their next meal: tall grass, leaf litter, bushes. Doing things like wearing your pants tucked into their socks can help ticks from reaching your skin but even we admit it’ll make you look kind of a doof.
Insect repellents can help prevent ticks from attaching. Ones containing DEET or picaridin definitely can ward off ticks, but you should pay attention to the manufacturer’s guides for how often to reapply as sometimes you need to reapply more frequently than you would for mosquitos. There are also plant-based repellents like citronella (they tend to be marketed as being more “natural”) but they’re generally less effective and work only for very short periods of time. You can buy clothing with a tick-killing agent called permethrin embedded in the fabric. Clothing that comes pretreated with permethrin can survive many washings (50 to 70). You can also buy permethrin and treat your own (non-doofy) clothes with it yourself, but then it usually lasts less than 10 washes.
They get around twice as big after each meal. If that continued, it would take eight or nine meals before the tick got to be the size of a cat. Luckily that isn’t how it works and they stop growing once they become adults.
The adults give birth to eggs, which hatch in springtime and the cycle starts all over again. Fortunately for us, the larva don’t hatch infected with Borrelia – they usually pick it up from an infected animal when they feed for the first time. Ticks can pick up the infection from any infected animal at any stage of their life cycle. Once they are infected they stay infected for the rest of their lives, because there aren’t any tick doctors to cure them. Infected ticks will pass the bacteria on to any animal they feed on, not just humans – this is how the bacteria persist in the environment.
The fact that the tick is essential for the transmission of Lyme disease gives us a lot of unusual ways to prevent the disease. Stopping ticks from biting people is the obvious way – we do this by wearing insect repellent and covering up when we’re outside. If we managed to clear the infection from the wild mice, then the tick larvae would never pick the bacteria up and then it wouldn’t matter even if they did feed on humans. We can also try to control the numbers of ticks in the wild. We can do this by spraying insecticides, or by managing the populations of animals like deer which are breeding grounds for ticks.
One study in Finland found that when they released wolves into a national park, the deer population went down because the wolves ate some deer. This caused tick numbers to go down, and therefore so did rates of Lyme disease. It’s possible that we could reduce Lyme disease by releasing loads and loads of wolves across America, but admittedly that might cause other problems. Personally I still think it’s worth a shot.