Amblyomma maculatum

Koch, 1844

Gulf Coast tick

Amblyomma maculatum, commonly known as the Gulf Coast , is a three- hard tick native to the southeastern and south-central United States. The has been expanding its range northward and westward in recent decades, with established now documented as far north as Virginia and west to Oklahoma. primarily parasitize large mammals including cattle, deer, and humans, while stages feed on small mammals and ground-dwelling birds. The species is a of parkeri, the causative agent of American tick bite fever, and has been associated with in rare cases. Heavy on livestock can cause significant economic damage through hide degradation and blood loss.

Amblyomma maculatum by (c) drnancyjackson, some rights reserved (CC BY). Used under a CC-BY license.

Amblyomma maculatum by (c) Haley Daniels, some rights reserved (CC BY), uploaded by Haley Daniels. Used under a CC-BY license.

Amblyomma maculatum by (c) Chris Hughes, some rights reserved (CC BY), uploaded by Chris Hughes. Used under a CC-BY license.

Pronunciation

How to pronounce Amblyomma maculatum: //ˌæm.bliˈɒm.ə ˌmæk.jʊˈleɪ.təm//

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Identification

Distinguished from the sympatric lone star (Amblyomma americanum) by the paired spots on the female rather than a single central spot; males lack the festoons with angular projections characteristic of Dermacentor . The scutal pattern separates it from the plain-scutum American dog tick (Dermacentor variabilis). In the western part of its range, it may overlap with Amblyomma triste, which has a more uniformly dark scutum. stages are difficult to distinguish morphologically from other Amblyomma species and require expert examination or molecular identification. Seasonal activity differs from A. americanum, with A. maculatum peaking in late summer and early fall rather than spring.

Images

Appearance

Gulf Coast ticks are relatively large hard ticks with scutums. Females possess a distinctive dark brown to black with white or cream-colored markings, including a pair of spots that give the its specific epithet 'maculatum' (spotted). The scutum covers only the portion of the female body, leaving the idiosoma capable of enormous expansion during blood feeding. Males have a conscutum covering nearly the entire surface with similar ornate patterning. Unfed adults are approximately 4–6 mm in length; fully engorged females may reach 15 mm or more. The mouthparts (capitulum) are long and prominent, extending well anterior to the body. Legs are banded with pale and dark segments.

Habitat

Occurs in coastal plains and prairie , with highest densities in grasslands, pastures, and open woodlands. In the southeastern United States, it inhabits pine savannas, coastal scrub, and agricultural landscapes. In Texas and Oklahoma, it is abundant in tallgrass prairie and post-oak savanna. The shows a strong association with open, sunny rather than dense forest. Within these landscapes, it occupies the herbaceous layer and low shrubs, questing from vegetation 15–45 cm above ground level. Soil moisture requirements appear intermediate; decline in both xeric conditions and areas prone to prolonged flooding.

Distribution

Native range extends along the Atlantic and Gulf coastal plains from Virginia south through the Carolinas, Georgia, Florida, and west along the Gulf Coast through Alabama, Mississippi, Louisiana, and Texas. Western range limit extends through central Oklahoma and eastern Kansas. The has been expanding northward, with recent establishment in Virginia documented. Disjunct occur in parts of the Caribbean and Central America (Mexico, Belize, Honduras, Nicaragua, Rica, Panama). Climate modeling predicts continued northward expansion into the mid-Atlantic and potential westward expansion under warming scenarios. In Colombia, it occurs in Andean regions with potential for Caribbean and Orinoco expansion.

Seasonality

activity peaks in late summer and early fall (July–October in most of the range), with some regional variation. In Texas, peak in August–September. This seasonal pattern contrasts with the spring–summer peak of the lone star . stages (larvae and nymphs) are active primarily in spring and summer, with larvae appearing earlier than nymphs. The exhibits a single per year in most of its range, with overlapping cohorts producing year-round presence of some life stages in southern portions of the distribution. Questing height varies seasonally, with adults climbing higher on vegetation during peak activity periods.

Host Associations

Cattle (Bos taurus) - primary for attach around ears, , and poll; heavy cause hide damage and 'gotch ear'
White-tailed deer (Odocoileus virginianus) - primary for Important wildlife supporting
Cotton rat (Sigmodon hispidus) - preferred for immaturesParticularly favored for larvae and nymphs
Marsh rice rat (Oryzomys palustris) - for immaturesDocumented in coastal
Eastern woodrat (Neotoma floridana) - for immaturesGround-dwelling rodent
Cotton mouse (Peromyscus gossypinus) - for immaturesSmall mammal in southeastern range
Sylvilagus palustris (marsh rabbit) - for immaturesGround-dwelling lagomorph
Ground-dwelling birds - for immaturesIncludes Geothlypis trichas, Cardinalis cardinalis, Passerina ciris, Sialia sialis, Thryothorus ludovicianus, Troglodytes aedon, Zonotrichia albicollis
Humans (Homo sapiens) - incidental for Bites can transmit parkeri
Domestic dog (Canis lupus familiaris) - for Companion animal
Fallow deer (Dama dama) - for Documented ungulate
Domestic pig (Sus scrofa domesticus) - for Livestock
Coyote (Canis latrans) - for Documented in Oklahoma range expansion

Life Cycle

Three- with each stage requiring a separate blood meal on a different individual host. hatch into six-legged larvae that seek small mammal or bird hosts, feed for 3–5 days, then detach and to eight-legged nymphs. Nymphs quest for hosts similar to larvae, feed for 3–7 days, detach, and molt to . Adults quest on larger mammals, with females taking a single prolonged blood meal (7–10 days or more) before dropping to oviposit. Males may take multiple smaller meals and mate with feeding females. A single is completed in approximately one year under favorable conditions, though individual ticks may live 2–3 years. Females produce 3,000–8,000 eggs in a single oviposition event.

Behavior

Quests from vegetation using foreleg to detect cues (CO₂, heat, vibration). climb higher on vegetation (15–45 cm) than immatures, which remain near ground level. Shows questing activity with peak host-seeking during daylight hours. Host-seeking is driven by and temperature cues. Unlike some , A. maculatum does not exhibit prominent behavior at host trails. In laboratory settings, nymphs show reduced movement compared to A. americanum under similar conditions. Off-host survival is relatively poor compared to sympatric species; adults experience high mortality during prolonged off-host periods, particularly in flooded or extremely dry conditions.

Ecological Role

for parkeri, the agent of American bite fever (a spotted fever rickettsiosis), maintaining this in enzootic cycles involving small mammals and birds. Serves as a bridge vector between wildlife and domestic animals/humans. Heavy on cattle can cause direct economic damage through hide degradation, blood loss, and secondary . The contributes to tick diversity in grassland and savanna and may compete with other tick species for . As a feeder on large mammals, it connects multiple host species in transmission networks.

Human Relevance

Primary of parkeri, causing American bite fever with including fever, headache, myalgia, and eschar formation at bite site. Bites can cause local inflammation and, in rare cases, (documented in alpha-gal knockout mice and suspected in other vertebrates). Economic impact on cattle industry through hide damage and control costs; reduce hide quality and may necessitate acaricide treatments. Occupational hazard for agricultural , wildlife biologists, and outdoor recreationists in areas. Climate change is expected to expand the ' range, increasing human exposure risk in the mid-Atlantic and potentially Midwestern states.

Similar Taxa

Amblyomma americanum (lone star tick)Overlapping range and use; distinguished by single central scutal spot on females versus paired spots on A. maculatum; also differs in seasonal activity (spring–summer peak vs. late summer–fall)
Amblyomma tristePotential western range overlap; A. triste has more uniformly dark, less and different associations
Dermacentor variabilis (American dog tick)Sympatric in eastern range; distinguished by plain brown without patterning and presence of festoons on idiosoma
Amblyomma cajennense complexOverlapping distribution in Central and South America; requires expert morphological or molecular differentiation

More Details

Microbiome

The A. maculatum microbiome comprises ten core bacterial , with , Francisella, and Candidatus Midichloria as key players. Rickettsia parkeri alters microbiome composition, replacing Francisella and increasing Candidatus Midichloria abundance. These - interactions may influence competence and offer targets for novel control strategies.

Climate change impacts

distribution modeling predicts northward and westward range expansion under climate change scenarios, with suitable increasing in the mid-Atlantic and Midwest by 2070. The species shows higher sensitivity to flooding and desiccation than A. americanum, making its distribution more dependent on soil moisture regimes.

Organic control methods

Field trials in Texas demonstrated that the silicate dust CimeXa achieves 96% reduction in larval and 100% reduction in nymphal A. maculatum when applied to vegetation, offering a potential organic alternative to synthetic acaricides in sensitive .