If you live on the East Coast, you already know that you share your environment with ticks. And truthfully, the best defense against ticks is information. The more you know about ticks, the more you are able to avoid being bitten. So, if you are willing to put aside the “ick-factor” for a bit, and get into the weeds of it all, here is the straight skippy on ticks.
First, not all ticks are equal. In the eastern United States, “blacklegged ticks,” commonly known as “deer ticks” are the species known to spread Lyme. (The scientific name for deer ticks is “Ixodes scapularis,” for those who want extra credit.) They also spread, as babasiosis, and anaplasmosis. If you are looking at one of the creatures in the picture below, you are looking at a deer tick, somewhere in its life cycle:
Deer ticks have a 2-3 year life cycle, during which they feed only three times. In year one, the eggs hatch into larvae, which feed once for about 4 days, usually on a single small animal like a mouse or a bird. After feeding, the larva drop off the host before molting into nymphs. The larvae are not born infected with lyme – larvae or nymphs become infected when they feed on infected hosts. They then pass diseases later in their lives when they feed on to subsequent hosts.
At 1/16 to 1/32 of an inch (about the size of a pin head!) and often nearly transparent, nymphs are much harder to see than adults. It is thought that most people who are infected by tick borne diseases have been bitten by nymphs rather than by adults.
At the end of the first summer, the nymph lies dormant, emerging again the following spring. From then to July, the nymph feeds on a second host before molting into an adult. During this feed, the nymph can transmit a disease.
In the fall or spring, female adults will attach to a large mammal. Deer do nicely, but so will a raccoon, a skunk, a dog, a cat, or a person. These hungry adults are easier to see because they are darker and a bit bigger, about the size of a sesame seed. Once attached, females feed again, mate, lay eggs and then die. Adult males attach to a large host but don‛t feed. So unlike the adult females, the adult males don‛t transmit disease.
When walking in the woods, it’s a relief to know that ticks can’t jump and they can’t fly. If you find a tick on your head, chances are it didn’t come from a tree or a branch above you. Rather, it started much lower down, and crawled up. Larvae and nymphs are generally ground dwelling. Adults climb onto shrubs waiting for larger hosts to brush by.
How do they find us? Deer ticks don’t find their hosts by sight; they have no eyes. On the tips of their front legs they have sensors, the Haller’s organs, that allow them to detect, from as far away as a few yards, the heat given off by warm-blooded animals and the molecules of carbon dioxide that we mammals exhale. When the “mammal nearby” message is received, a tick’s two front legs, equipped with claws that act like grappling hooks, thrust into the air while its three pairs of back legs hold on to a blade of grass, a twig, or a leaf. When a host brushes against a tick – voila! — the tick hitches a ride.
Once on the body, ticks will often climb upwards looking for warm spots with good blood flow. That is why they are frequently found in the groin area, under arms behind ears and in hair.
Deer ticks—the ones that carry Lyme disease—are not as aggressive as dog ticks, and they generally stop crawling whenever they find a clothing barrier, which is why you’re likely to find them around your sock line, along your underwear line, and on the backs of your knees where your shorts stop.
Lawns, fairways and playing fields are not a particularly good habitat for ticks. Most ticks on a lawn are found within nine feet of its perimeter. Ticks are also found in the woods, in leaf litter, on shrubs, on groundcovers and in long grasses and prefer damp areas.
Getting bitten by an infected tick will not automatically make you sick. For most tick-borne diseases, the tick needs to be attached for longer than 24 hours to transmit disease, because of the biology of the way ticks feed. Bacterial diseases live in ticks’ stomachs, but in order to be transmitted they need to get to the saliva, a process that takes at least 24 hours. According to the Tick Management Handbook put out by the Connecticut Agricultural Experiment Station, “the probability of transmission of Lyme disease spirochetes increases the longer an infected tick is attached (0% at 24 hours, 12% at 48 hours, 79% at 72 hours, and 94% at 96 hours in one recent study). The estimated average time for attachment before detection and removal was 30 hours for nymphs and 10 hours for adult ticks, nymphal ticks were twice as likely as adult ticks to be partially engorged.”
This this is TMI? Think again. With all this information, it gets easier to make smart choices that can deter tick bite.