NPIPM:Ixodida
Authors: Ashley Mueller, Buyung Hadi
Identification
Ticks are not insects. They are arachnids, and they are more closely related to mites and spiders than insects. All arachnids have four pairs of legs with no antennae or wings.
Generally, there are two families of ticks: hard ticks (Ixodidae) and soft ticks (Argasidae). The “hard” and “soft” parts of the family names refer to the shield-like structure at the back of the hard ticks’ bodies. The soft ticks lack this structure. Both hard and soft ticks can be present in the same geographic area; however, their habitats differ. Hard ticks are commonly found in wooded or weedy areas containing a good number of hosts like deer, cattle, dogs, and small mammals. Soft ticks, encountered infrequently by humans, are generally found in animal burrows or dens, dilapidated human dwellings and animal shelters. Soft ticks are often parasites of birds and bats.
Most of the commonly encountered ticks in the northern plains, like the American dog tick and lone star tick, are hard ticks. These ticks have mouthparts that are easily visible. Ticks do not have a true head. Their head is somewhat merged with their thorax (chess region) forming a region called cephalothorax. Ticks’ mouthparts project forward from the front of the cephalothorax. Most often, the size and shape of the mouthparts are used to determine the tick species. Female tick bodies are able to stretch as they feed on blood, which causes them to become enlarged and swollen. Male ticks can only take in small amounts of blood due to a hard, shield-like plate that covers the top of their body surface.
The immature American dog ticks feed on small mammals and are active in winter and spring. The adults are abundant in late spring and early summer and feed on dogs and bigger mammals including humans. Immature Rocky mountain wood ticks are most abundant in summer, feeding on small mammals. The nymph and adult ticks are active in late spring and early summer and they feed on medium- and large-sized mammals.
Black-legged tick (Ixodes scapularis) is generally smaller than the American dog tick (Figure 5). The adult male black-legged tick is about 0.04 inch in length while the female tick is about 0.08 inches long. The female body is reddish with a brown dorsal shield while the male’s dorsal shield is dark brown and extends across its body length. It is important to confirm the presence of black-legged ticks in the state.
Habitat
Adult and immature ticks are most commonly found in wooded or brushy areas, which are good habitats for their hosts. Immature ticks typically feed on birds and smaller animals; adults and some nymphs primarily feed on larger animals, including humans and their pets.
The process in which ticks locate their hosts is called questing. Ticks climb to the tips of grass or leaves, and they extend their front legs away from their bodies while they remain attached to vegetation with the remaining legs. When a potential hosts walks by, the questing tick hooks onto the host with its front legs. After the tick settles on the host, it inserts its mouthparts to begin feeding. Ticks are sensitive to carbon dioxide emitted from potential hosts, and they are able to travel short distances to locate the carbon dioxide source.
Life Cycle and Seasonal History
The tick life cycle has four stages that includes egg, six-legged larva or seed tick, nymph, and adult. The two common types of ticks found in the northern plains are three-host ticks. A few thousand eggs are laid on the ground, and after hatching, the larvae find and feed on a host. Once a larva is full, it drops off the host and molts to the nymph stage. The nymph finds a different host, and it drops off to molt to the adult stage. Adults find another host on which to feed and mate, and they drop off to lay eggs. The length of feeding for each development stage is one to three days.
Ticks are able to overwinter as a fed larva, as an unfed nymph, or as an unfed adult. Unfed adult ticks can live nearly two years.
Human Interaction and Urban Impact
Although ticks are not economically important, they are cause for health concern. Ticks are parasites that feed on the blood of humans and companion animals. Ticks use their mouthparts to cut a small hole in the host’s skin, and they insert their mouthparts into the host’s tissue to feed on blood. Some tick species have been known to vector human pathogens.
Diseases spread by ticks include Rocky Mountain spotted fever (RMSF), Lyme disease, and Ehrlichiosis. RMSF is characterized by a fever and rash in persons bit by ticks carrying the disease. The fever appears first, and the rash typically begins several days after. It usually starts in wrists and ankles, and it extends to the trunk. This disease is transmitted by the American dog tick.
Lyme disease is caused by infected black-legged (deer) ticks. Lyme disease begins with a rash at the location of the tick bite; the rash looks like a bulls-eye, with a red center and red concentric circles. The flu-like symptoms include fever, headache, chills, lethargy, and muscle and joint pain. Ehrichiosis is similar to Lyme disease in that it is a bacterial disease. Its symptoms are similar to Lyme disease.
If a rash and flu-like symptoms appear after spending time in a tick-infested area, a physician should be contacted. Diseases caused by ticks are treatable with antibiotics if detected early.
Prevention and Management Approaches
Take preventative measures when spending extended time outdoors. To prevent ticks from getting too close to a building, keep grasses short and brush trimmed. Avoid tick bites by staying away from areas known to be infested by ticks. If a tick-infested area cannot be avoided, wear long-sleeved shirts and long pants in a light color, ensuring ticks can be easily seen. Tuck pants into socks to prevent ticks from crawling up the inside of pants.
Insect repellent with a 10%-30% active ingredient of DEET (diethyl toluamide) should be applied on exposed skin and clothing. If an insect repellent is used, always read the label and follow application directions. If the smell and skin-feel of DEET is bothersome, use products containing IR3535. Tick repellents containing permethrin should not be used on a person’s skin; they should only be used to treat clothing. Tick repellents approved for human use should not be used on pets; consult with a veterinarian regarding a topical tick preventative for companion animals.
Make it a habit to examine one’s body for ticks after spending time in locations with known or potential tick presence. Once out of the potentially-infested area, perform a thorough body check to determine the presence of ticks. If a tick is found, it should be removed immediately using fine-tipped tweezers. The tick should be grasped as close to the skin as possible, and it should be pulled out with steady pressure. Be careful not to squeeze, twist, or puncture the body of the tick because it can contain infectious organisms. Once the tick is removed, disinfect the bite location thoroughly and wash hands.
Using another method to remove a tick is not advised. Ticks are deeply embedded during feeding, and they cannot voluntarily release themselves from host tissue. The only time they are able to release themselves is after they have been fully fed.
Stray ticks found indoors may be vacuumed; a crevice tool allows to get in places ticks may be hiding. Dispose of the vacuum content immediately after using to prevent ticks from crawling out and re-entering the home.
Other Online Resources
University of Nebraska-Lincoln
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