Observation of brood size and altricial development in Centruroides hentzi (Arachnida: Buthidae) in Florida, USA

Centruroides hentzi (Banks) (Hentz striped scorpion; Arachnida: Buthidae) is a species of bark scorpion native to the southeastern United States (Shelley and Sissom 1995). Previously thought to be endemic to Florida, it is further distributed as far north as North Carolina and west to Mississippi due to human introductions, with observations in Georgia and Alabama considered part of its natural range. This arachnid is particularly prevalent in Florida, where it inhabits a variety of habitats including pine forests, hardwood oak hammocks, and human-altered environments (Muma 1967; Shelley and Sissom 1995; Stevenson et al. 2012). C. hentzi is a semi-arboreal scorpion, and is often found under tree bark, in rotting logs, under rocks, high on trees or in leaf litter, or within human dwellings (S. Shukla, personal observation; Stevenson et al. 2012; Muma 1967). This makes C. hentzi one of the scorpion species most commonly encountered by people within its range (Folkerts et al. 1993).

Centruroides hentzi is a medium-sized scorpion, typically reaching lengths of 60 mm as adults (Stevenson et al. 2012). Exhibiting sexual dimorphism, females of this species are usually larger and wider than males (Muma 1967). Other morphological differences extend to males bearing an extra pectinal tooth and longer metasomal segments (Stevenson et al. 2012). Both sexes of this species are characterized by their distinctive coloration, featuring a pale yellow to tan body with dark longitudinal stripes running the length of its carapace.

Similar to most species of scorpions, C. hentzi has two venom glands residing on the end of the telson (Ward et al. 2018). Different selective pressures have caused venom to be expressed differently between male and female scorpions (Ward et al. 2018). This has led their venom to be highly variable between and among populations, specifically among females within populations. While its venom is not considered medically significant for healthy adults, its sting can cause pain and discomfort (S. Shukla, personal observation; Muma 1967; Stevenson et al. 2012).

Like other members of the genus Centruroides, C. hentzi is likely primarily nocturnal, leaving their daytime hideaways to forage for prey at night (Stevenson et al. 2012; Bibbs et al. 2014; Davison et al. 2020). C. hentzi primarily feeds on other terrestrial arthropods, including termites, small crickets and cockroaches (Muma 1967).

Scorpion reproductive cycles depend upon seasonal changes and warm temperatures, beginning in the late spring and continuing through early fall months (Stockmann 2015). Males will initiate mating through a courtship behavior, involving a ‘dance’ in which he uses his pedipalps to grab onto the female, followed by a synchronized dance that is completed together. The fertilized embryos gestate within the mesosoma of the female, nourished by a placental connection (Williams 1969). Little is known about the gestation period of C. hentzi. Other members of its genus (Centruroides vittatus (Say) and Centruroides insulanus (Thorell)), however, have a gestational period of up to approximately 8 months; which is variable with environmental conditions (Farley 2005; Williams 1969).

In general, following gestation, gravid female scorpions will carry out ovoviviparous reproduction, giving birth to live young (Stockmann 2015). The young scorplings will be carried on her back for anywhere between 1 and 51 days succeeding their birth. The young remaining with their mother is attributable to contact pheromones expressed in the mother’s cuticle. Once the scorplings’ exoskeletons harden, they will disperse from their mother. This pattern of maternal care has been observed across multiple scorpion species but may vary depending on environmental conditions and species-specific behaviors.

Despite the ecological significance of C. hentzi, detailed information on its reproductive biology, particularly regarding brood size and developmental stages, remains limited in the scientific literature (Stevenson et al. 2012). In a study of a related species, C. vittatus, Miranda (2001) reported an average brood size of 16 scorplings, with a range from 1 to 30. Further research on other Centruroides species has revealed significant variability in reproductive parameters (Brown and Formanowicz 1995; Francke and Jones 1982), underscoring the importance of gathering species-specific data for C. hentzi. Understanding the reproductive biology of this species is crucial for providing insights into the population dynamics and life history strategies of these arachnids, which is essential for further ecological studies and conservation efforts.

This natural history note aims to contribute to filling this knowledge gap by reporting observations on the number of offspring, timing of parturition, and maternal behavior in a female C. hentzi. Such information is valuable not only for understanding the species’ biology but also for comparing reproductive strategies within the genus Centruroides and among scorpions more broadly.

On 31 July 2024, an adult C. hentzi was collected in remnant sandhill habitat on the southern section of the Brooksville Ridge in northern Hernando County, Florida (28.6882°N, 82.504°W), adjacent to patches of open scrub (Figure 1A). Dominant vegetation in the area consisted of Pinus palustris (Miller) (Pinaceae), Pinus clausa (Sargent) (Pinaceae), Quercus laevis (Walter) (Fagaceae), Quercus geminata (Small) (Fagaceae), and Quercus margarettae (Small) (Fagaceae). The gravid nature of the scorpion was not known to the authors at that time.

Figure 1:

Observations of Centruroides hentzi life stages. A) Adult, gravid female C. hentzi without the presence of offspring. B) Adult female C. hentzi carrying 20 offspring on her back (black arrows). C) Juvenile C. hentzi after disembarking the mother’s back following its first molt.

Upon relocation to Butterfly Tampa (Florida), a zoological facility, the individual was housed apart from conspecifics and monitored daily. At approximately 1:00 PM on 19 August 2024, a new brood of scorplings was discovered on the mother’s back, none yet with fluorescent hyaline layers (Figure 1B). Fourteen days after parturition, at approximately 9:00 AM on 1 September 2024, the young were noted to have begun dispersal from the mother (Figure 1C), and all had departed by 3 h later at around 12:00 PM. At this time, they all displayed fluorescence for the first time under an ultraviolet lamp.

This observation joins that of two congeners, Centruroides gracilis (Latreille) (Arachnida: Buthidae) and C. vittatus, which also have had their time from parturition to dispersal observed. In C. gracilis, 12 and 15 days (n = 2) was noted by Franke and Jones (1982). In C. vittatus, Formanowicz and Shaffer (1993) recorded a range of times from 7 to 12 days (n = 34), with a mean of 8.83 days to dispersal. Miranda (2001) found a wider range of 4–11 days (n = 49), with a mean of 9 days to dispersal. Across three populations of C. vittatus (n = 73), Brown and Formanowicz (1995) found an overall range of 5–10 days, with the means of each population ranging from 6.74 to 9.09 days to dispersal. Though potentially subject to influence by factors beyond the purview of this publication (Brown and Formanowicz 1995), our observation of 14 days from parturition to dispersal falls outside of the range of all observations for C. vittatus, and within that for the sympatric C. gracilis, with possible implications for trends in altriciality within Centruroides along ecological gradients or phylogenetic allegiances.

Twenty scorplings in total were enumerated and housed separately following their departure, but no aggressive or cannibalistic behavior was noted from the mother prior to rehousing. Each showed immediate capability to subdue and consume live prey upon being offered 1.5 mm flightless Drosophila melanogaster (Meigen) (common fruit fly; Diptera: Drosophilidae), and approximately two weeks later, 5 mm Acheta domesticus (Linnaeus) (domestic house cricket; Orthoptera: Gryllidae). Two molts were observed in the juvenile scorpions: the first occurred on 19 October 2024, 48 days after departing from the mother, and the second on 23 October 2024, 52 days post-departure.

On 7 April 2025, during our routine daily checks, the same female produced a second brood in the absence of any introduced male. We observed one scorpling still on the mother’s back, one being actively consumed by her, one solitary individual in the enclosure, and a clump of nine juveniles; additional offspring may have been cannibalized before we inspected. None of these neonates fluoresced under ultraviolet light—indicating they dispersed prematurely before their first molt—and the entire secondary brood perished by 19 April 2025.

This novel observation of a gravid C. hentzi provides valuable insights into the reproductive behaviors of this species, particularly within Florida’s ecosystems. The brood sizes observed align with previously recorded sizes for other scorpion species, which typically range from 1 to 30 (Brown and Formanowicz 1995). Notably, the absence of fluorescent hyaline layers at birth, followed by the emergence of fluorescence under ultraviolet light only after a non-premature dispersal, may indicate key developmental milestones critical for survival and predation. Daily observations confirmed that fluorescence was not present until after the first molt, which coincided with dispersal from the mother. This phenomenon warrants further investigation into the ecological significance of fluorescence in early life stages. While the exact purpose of this fluorescence is not known, several hypotheses have been presented. It may be that the fluorescence serves to increase the sensitivity of the scorpion’s eyes to ultraviolet light (Blass and Gaffin 2008). Other hypotheses include aposematic display or prey attraction (Kloock 2005), amplification of the light field (Camp and Gaffin 1999), identification of conspecifics for mating (Kloock 2008), and the use of fluorescent proteins as a sunscreen (Lourenco and Cloudsley-Thompson 1996).

Although the female was wild-caught and her prior mating history is unknown, the production of a second brood in captivity—without any intervening mating opportunity—suggests that C. hentzi females are capable of storing sperm to fertilize multiple broods over time, which raises the possibility of cryptic female choice (CFC). Alternatively, the production of a second brood may indicate the potential for thelytokous parthenogenesis, although this can only be confirmed through genetic testing. Moreover, the partial consumption of the secondary brood raises the possibility of selective filial cannibalism, wherein females may selectively cull offspring post-parturition. As observations of the initial brood revealed no maternal aggression or cannibalism, consistent with established scorpion maternal care patterns (Miranda 2001), this underscores potential plasticity in care behaviors in C. hentzi. Further studies and observations will need to be made to draw conclusions about what is standard within this species in regard to maternal care and developmental behaviors.