Ticks are small arthropods similar to insects. Instead of having six legs and three body parts as insects do, ticks have eight legs and two body parts. All ticks are blood feeders; some species are important vectors of diseases in humans and other animals. The black-legged tick - aka deer tick - (Ixodes scapularis), vectors Lyme disease. We are lucky this species is not found in Nebraska.
Even though spiders also have eight legs and two body parts, ticks are more closely related to mites. In addition to having eight legs, both mites and ticks have mouthparts with similar structures. Tick mouthparts are located on the capitulum - or head - and can be easily seen from above. During feeding, the hypostome, the feeding apparatus, remains firmly anchored in the skin because of backward-directed spines on it. These projections make removing a tick cleanly - without leaving mouthparts embedded in the skin - hard to do.
Ticks most commonly encountered in southeastern Nebraska are the American dog tick and the lone star tick. Both species are hard ticks which have a scutum just behind their head. It is easy to tell the difference between adult male and female hard ticks. The male tick is smaller than the female. His scutum covers the entire surface of his body and constricts the blood meal. The female has a smaller scutum which allows the body to expand greatly so she can ingest enough blood to produce thousands of eggs.
Ticks undergo four developmental stages: egg, larva, nymph, and adult. The first stage, larval ticks, have 6 legs; nymph and adults have eight. All stages of ticks must feed on blood to molt to the next life stage.
Most hard ticks are "three-host" ticks. During its lifetime, a tick will feed on three different hosts, one for each of its developmental stages. After feeding, the tick will drop from its host into the leaf litter to either molt or, in the case of a female, lay eggs.
Because a blood meal is required for each stage of development, the entire life cycle, from egg to adult, may take two years or more to complete.
During periods of adverse environmental conditions such as heat, drought, or cold, ticks will live in leaf litter which provides enough moisture and protection against the elements so they can withstand a colder than normal winter or dry spells.
How do ticks find their host? When I was a kid living in northern Michigan, I was told ticks fall out of trees. This isn't true and falls into the realm of an old wives' tale. Ticks do not jump or fly either. To find a blood meal, ticks must literally come in contact with a host, and have developed strategies to help them find a host. The most interesting behavior is called "questing." Questing ticks crawl up the stems of grasses and hang onto the blade with their front legs extended. Their front legs have specialized organs on them to detect carbon dioxide gradients from approaching hosts. When a host brushes against the extended front legs, the tick quickly clings to the animal or human. Favorite vegetation sites for adult questing ticks include tall grasses and shrubs. Immature ticks may remain lower in the vegetation near the leaf litter where they may likely come into contact with small rodents and ground-visiting birds.
Do ticks have ways of knowing where animals and humans are more likely to walk? Maybe. Last summer at Ashfall Fossil Bed State Historical Park, I saw a questing American dog tick hanging onto a blade of grass next to a park pathway and took this photo. I then decided to check other plants along the pathway and found questing ticks spaced every 6 feet or so on grasses right next to the pathway. It's a good reason to stay in the middle of the path!