What To Know About Blacklegged Ticks – Ixodes scapularis
This notoriously ubiquitous arachnid can be found any day of the year when temps are above freezing, waiting for an unsuspecting host to feed upon. I.scapularis is a questing tick that can detect a host from a distance and will extend its front legs out while the host nears so to latch onto it.
I.scapularis has the ability to carry a multitude of disease-causing agents in its gut which will transfer into the host possibly causing one or more infections. This can be problematic in diagnosing, especially when most people do not know they were ever bitten by a tick in the first place.
I.scapularis nymph stage tick is predominantly responsible for infecting humans with Lyme disease and other tick-borne disorders.
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Blacklegged Tick Understanding
Blacklegged ticks are arachnids not insects, they are related to mites and spiders. They do not have a head, antennae or a segmented body. They do not eat or drink anything but do take 3 blood meals in their lifetime in order to transition to each life stage and lay their eggs. They do not hunt, jump or fly. Immature stages quest at ground level, adults quest up to 3 feet in vegetation waiting for a host to brush into it. They secrete a cement-like substance while attaching to skin as well as anesthetic, anti-coagulant and anti-inflammatory substances during their blood meal. Blacklegged ticks have no significant natural predator and are undetectable by birds.
Larvae are pale in color and partially translucent, have 6 legs and are very difficult to see due to their very small size. Nymphs are darker in color, have 8 legs and are the size of a poppy seed and will go undetected as they feed. Adult females have long mouthparts, bodies that are tear-drop shaped the size of a sesame seed, they have a black scutum and a dark orange brown body with black legs. The male is all black, smaller than females and have shorter mouthparts.
Habitat & Range
Blacklegged ticks are predominately found in deciduous forests and tall grasslands throughout the northeastern and midwestern United States. More specifically the bordering transitional area known as an ecotone or biocenosis. This specific area in these habitats comprises large numbers of mammals and ground dwelling birds as well as having a leaf-littered floor, brushy and weedy vegetation that creates animal harborage, tick questing platforms and a stratified humidity layer that ticks require to maintain their water balance. This area could be the border of an athletic field or a typical backyard.
Life Cycle & Hosts
The blacklegged tick is a 3-host tick with a 2-year life cycle. I.scapularis goes through four stages in its life cycle: egg, larva, nymph, and adult male/female. Egg masses of up to 3000 eggs are laid in late spring. Eggs hatch in early summer and thousands of emerged larvae feed once July through September. The engorged larvae will go through a molting transformation, over-winter and emerge as nymphs in late spring. They will only feed once May through August. The engorged nymph will go into a molting transformation and emerge as an adult male or female in late September early October. The adults will mate on large mammalian hosts then feed once September through the following spring. The male will die after mating and the female will lay its egg mass and die sometime in May.
Generally, Larval ticks are not infected with Lyme disease causing bacteria, Larvae become infected when they feed on infected reservoir hosts like the white-footed mouse, eastern chipmunk and less commonly certain bird species. After feeding, the larvae detach and molt into 8 legged nymphs. Approximately 25% of larvae become infected and carry the bacteria into the nymphal stage. (% varies geographically).
Like larvae, nymphs are opportunist and feed on hosts close to the ground. The newly emerged nymphal stage ticks will feed and infect young rodents like the eastern chipmunk and the white-footed mouse creating new infected reservoir hosts. Once engorged, the detached nymph will molt and emerge in early fall as male or female adults. Approximately 50% of the nymphs become infected and carry the bacteria into the adult stage. (% varies geographically).
Adult ticks climb up grass and other plant stems up to 3’ and wait for unsuspecting hosts to pass by. An adult tick can survive for up to a year before it finds a host. Male and female ticks mate while questing on vegetation or while attached to the host. After several days, the engorged female will detach from the host and lays her eggs (1000-3000) where it falls, usually in leaf litter. The male tick will die after mating. White tailed deer are the principal reproductive host for the adult ticks and tick abundance is closely linked to the local populations of these animals.
Medical & Veterinary Importance
Lyme disease is the most commonly reported vector-borne illness in the United States. It is caused by the bacterium Borrelia burgdorferi, which is transmitted to humans through the bite of an infected Blacklegged tick. Lyme disease can cause a wide range of symptoms, including fever, headache, fatigue, and sometimes a distinctive bull’s-eye rash. If left untreated, it can lead to serious problems with the heart, joints and nervous system. I.scapularis can also transmit other diseases to both humans, pets and domesticated animals, including Anaplasmosis, Babesiosis, Ehrlichiosis, Powassan Virus and Tick-Borne Relapsing Fever. These diseases can cause similar symptoms to Lyme disease and can be just as serious if left untreated. Therefore, it is important to be aware of the risks associated with blacklegged ticks and take steps to protect yourself, pets and livestock from their bites.