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Tick Surveillance

Ixodes scapularis

Surveillance for Ixodes scapularis and pathogens found in this tick species in the United States [PDF – 34 pages] Print only

Ixodes scapularis—Estimated and established distribution, 2018

Estimated distribution (yellow) of the blacklegged tick (Ixodes scapularis). Counties where established populations have been documented (red). Counties classified as “established” are those where six or more I. scapularis of a single life stage or more than one life stage of the tick were collected in the county within a 12-month period.

Estimated distribution (yellow) of the blacklegged tick (Ixodes scapularis). Counties where established populations have been documented (red). Counties classified as “established” are those where six or more I. scapularis of a single life stage or more than one life stage of the tick were collected in the county within a 12-month period.

Ixodes scapularis lifecycle

Ixodes scapularis typically lays eggs in the spring. These hatch into larva in summer. The following spring, nymphs feed and then molt into adults later in the fall. Adults females will seek a blood meal and lay eggs the following spring, completing the lifecycle.

The lifecycle of Ixodes scapularis ticks generally lasts two years. During this time, they go through four life stages: egg, larva, nymph, and adult. After the eggs hatch, the ticks must have a blood meal at every stage to survive. Blacklegged ticks can feed from mammals, birds, reptiles, and amphibians. The ticks need a new host at each stage of their life.

Ixodes pacificus—Estimated and established distribution, 2018

Estimated distribution (yellow) of the Western blacklegged tick (Ixodes pacificus). Counties where established populations have been documented (red). Counties classified as “established” are those where six or more I. scapularis of a single life stage or more than one life stage of the tick were collected in the county within a 12-month period

Estimated distribution (yellow) of the Western blacklegged tick (Ixodes pacificus). Counties where established populations have been documented (red). Counties classified as “established” are those where six or more I. scapularis of a single life stage or more than one life stage of the tick were collected in the county within a 12-month period.

Ixodes pacificus lifecycle

Ixodes pacificus typically lays eggs in the spring. These hatch into larva in the following spring. During the summer, larvae feed and then molt into nymphs the following spring. During the summer, nymphs feed and then molt into adults over the winter. Adults females will seek a winter or spring blood meal before laying eggs in spring, completing the lifecycle.

The lifecycle of Ixodes pacificus ticks generally lasts three years. During this time, they go through four life stages: egg, larva, nymph, and adult. After the eggs hatch, the ticks must have a blood meal at every stage to survive. Blacklegged ticks can feed from mammals, birds, reptiles, and amphibians. The ticks need a new host at each stage of their life.

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