About Ticks

What Are Ticks?

These tiny arachnids might look like insects, but they're actually more closely related to spiders and scorpions. What sets ticks apart is their feeding strategy—unlike mosquitoes that bite and quickly move on, ticks latch onto their host and can remain attached for days, slowly feeding on blood. This extended attachment period is precisely what makes them such effective disease vectors.

Globally, scientists have identified over 900 tick species, with approximately 90 found across the United States. The good news? Not every tick carries pathogens. However, several species in North America are known to transmit serious diseases to both humans and animals, making identification and prevention crucial.

Deer tick (Ixodes scapularis) showing all life stages - adult male, female, nymph, and larva

Deer tick (Ixodes scapularis) showing all life stages - ticks are small arachnids that can transmit diseases to humans and animals. Image: Wikimedia Commons (CDC, Public Domain)

Two Main Types of Ticks

Ticks are divided into two main families, each with different characteristics:

Hard Ticks (Ixodidae)

Hard ticks are the most common type you'll encounter. They have a hard, shield-like plate on their back called a scutum. These ticks feed slowly, often staying attached for several days. Most disease-carrying ticks are hard ticks.

Common hard tick species include:

Black-legged tick (Deer tick) - Found in the northeastern and upper midwestern United States, transmits Lyme disease
American dog tick - Common in the eastern U.S., can transmit Rocky Mountain spotted fever
Lone star tick - Found in southeastern and eastern U.S., known for the white spot on females
Brown dog tick - Found worldwide, often associated with dogs

Reference: CDC DPDx - Ticks

Soft Ticks (Argasidae)

Soft ticks don't have a hard shield on their back - they have a leathery, wrinkled appearance. They feed much faster than hard ticks (usually in minutes to hours) and are often found in animal nests or burrows. While less common, they can still transmit diseases.

Reference: Sonenshine, D.E., & Roe, R.M. (2014). Biology of Ticks (Second Edition). Oxford University Press.

Understanding Tick Anatomy

Ticks have a unique body structure that helps them attach to and feed on their hosts:

Body Size: Unfed adult ticks are typically 3-5mm (about the size of a sesame seed). When fully fed, female ticks can grow to 10-15mm or larger - that's a 100-fold increase in body weight!
Legs: Adult ticks have 8 legs (like spiders), while young ticks (larvae) have only 6 legs
Mouthparts: Ticks have specialized mouthparts with backward-facing barbs that act like anchors, making them very difficult to remove once attached

Black-legged tick (Ixodes scapularis) showing body structure and life stages. Image: Wikimedia Commons (CDC, Public Domain)

Reference: CDC - DPDx - Ticks

The Tick Life Cycle

Understanding how ticks grow and develop helps explain why they're so successful at spreading diseases. Most ticks go through four life stages:

Four Life Stages

Egg: Female ticks lay thousands of eggs, usually in leaf litter or soil
Larva: Tiny 6-legged ticks that hatch from eggs and need their first blood meal
Nymph: 8-legged, about the size of a poppy seed - very hard to see but can transmit diseases
Adult: Full-grown ticks that mate and reproduce

Important: Most ticks need a blood meal at each stage to grow to the next stage. The entire life cycle can take 2-3 years for many species.

Reference: CDC - Tick Lifecycles

Life Cycle Example: Black-Legged Tick

The black-legged tick (deer tick) has a typical 2-year life cycle:

Year 1: Eggs hatch in late summer, larvae feed in August, then molt to nymphs
Year 2: Nymphs become active in spring (May-June), feed, then molt to adults
Fall/Winter: Adults become active when temperatures are above freezing

Reference: Kocan, K.M., de la Fuente, J., & Coburn, L.A. (2015). Insights into the development of Ixodes scapularis. Parasites & Vectors, 8, 592.

How Ticks Find and Feed on Hosts

Ticks have a unique way of finding their next meal. They don't jump or fly - instead, they use a behavior called "questing":

Questing: Ticks climb up grass, leaves, or other vegetation and wait with their front legs outstretched
Detection: They can sense heat, carbon dioxide, and vibrations from approaching animals
Attachment: When an animal brushes by, the tick grabs on and finds a place to attach
Feeding: Once attached, ticks can feed for several days. During feeding, they can transmit disease-causing germs

Reference: Gulia-Nuss, M., et al. (2016). Genomic insights into the Ixodes scapularis tick vector of Lyme disease. Nature Communications, 7, 10507.

Why Ticks Are So Successful

Ticks have several unique biological features that make them effective parasites:

Special Feeding Adaptations

Their saliva contains painkillers, so you often don't feel them bite
They can expand their body dramatically while feeding (up to 100 times their original size)
They can survive for months without feeding between life stages

Disease Transmission

Ticks can carry multiple disease-causing germs at once
They can transmit diseases during their long feeding period
Some ticks can pass diseases to their offspring