Microxylobius vestitus is a weevil species endemic to the island of St Helena and is found at a range of altitudes. This species was recorded in low numbers by Melliss (1875) and Wollaston (1877). It was found in high numbers both inside and outside of the endemic vegetation, during the extensive survey work on the island in the 1960s. Specimens were recorded from more than eight sites surveyed by Mendel, Ashmole and Ashmole in 2005–2006 and commonly by Pryce  (2021), but would still benefit from more survey work. It is found in association with endemic, native and introduced plant species, such as Samphire (Suaeda fruticosa), Scrubwood (Commidendrum rugosum – VU), from the dead wood of cabbage trees: these could include Black Cabbage (Melanodendron integrifolium – VU), She-cabbage (Lachanodes arborea – EW) and He-cabbage (Pladaroxylon leucodendron – CR) and the hollow stems of Jellico (Berula bracteata – VU), and non-native species including the dead wood of Furze (Ulex europaeus) and Erythrina species at mid- and lower-altitudes. Populations in the cloud forest are under threat from climate change, invasive non-native predatory invertebrates, and the recent spread of fungal diseases, including Phytophthora spp.. Non-native vertebrate predators, such as rodents and the African Grass Frog (Strongylopus grayi) may also negatively impact this species. Its extent of occurrence (EOO) is 35 km² and its area of occupancy (AOO) is 16 km², it occurs in four locations, and its habitat is undergoing continuing decline due to the threats outlined above. Further survey work is not considered required for this species at this point. Meanwhile, this species is assessed as Endangered.

Microxylobius vestitus is a weevil endemic to the island of St Helena in the South Atlantic. Known localities include: Rupert’s Valley, Longwood, Horse Point Plain, Teutonic Hall, Upper Fisher’s Valley, Rose Hill, Lemon Tree Gut, Mount Ross-Bate’s Branch, the High Central Ridge, Cabbage Tree Road, southeast Cuckholds Point/Mt Actaeon/Diana’s Peak, northeast of Cason’s Gate, High Peak and west of Central Ridge - above West Lodge, Deep Valley Head, Teutonic Hall, Grapevine Gut and Upper Legg’s Gut, southern branch.

Note: there are historical changes with the site names for Diana’s Peak, Cuckhold’s Point and Mt Actaeon and as such, we are including all the names in this assessment for the location of the records; see St Helena Government (2020).

According to Melliss (1875), this species was rare and confined to native and endemic vegetation at high altitudes in 1865 (the High Central Ridge); later surveys showed it to be present on introduced species as well. The species was described from one specimen collected by Melliss. Although found rarely by Melliss, it was found in large numbers at Cuckholds Point/Mt Actaeon/Diana’s Peak and Cason’s by Wollaston. It was found at lower numbers at High Peak and West Lodge (Blue Hill). A single specimen was collected at Plantation (lower altitude). The species was also found by H. Roberts. Between 1965 and 1967, 1,162 specimens were recorded from a range of sites: Rupert’s Valley, Longwood, Horse Point Plain, Teutonic Hall, Upper Fisher’s Valley, Rose Hill, Lemon Tree Gut, Mount Ross—Bate’s Branch, the High Central Ridge, Cabbage Tree Road, southeast of Diana’s Peak, northeast of Cason’s Gate, High Peak and west of Central Ridge—above West Lodge. This species was recorded from more than eight sites between 2005 and 2006 by Mendel, Ashmole and Ashmole (2008) including Cuckhold’s Point, Diana’s Peak, Mount Actaeon, Cabbage Tree Rd, High Peak, Casons Gate, Deep Valley Head, Teutonic Hall and Grapevine Gut. It was recorded at Mount Actaeon in 2011, at Upper Legg’s Gut, southern branch in 2013, Cabbage Tree Road in 2014, between Fairyland and Peak Gut in 2015. Pryce (2021) recorded 43 specimens of this species in 2016 from 13 sites (at Mount Actaeon, near the cannon) and described it as one of the commonest and widest spread weevils on the island. They collected the species by Berlese extraction of deadwood, leaf litter and organic debris.

Melliss thought this species was confined to native vegetation at high altitudes. However surveys during the 1960s found this species in association with both native and endemic species including Samphire (Suaeda fruticosa), Scrubwood (Commidendrum rugosum – Vulnerable), from the dead wood of cabbage trees: these could include Black Cabbage (Melanodendron integrifolium – Vulnerable), She-cabbage (Lachanodes arborea – Extinct in the Wild) and He-cabbage (Pladaroxylon leucodendron – Critically Endangered), and the hollow stems of Jellico (Berula bracteata – Vulnerable), and non-native species including the dead wood of Furze (Ulex europaeus) and Erythrina species at mid- and lower-altitudes.

This species was recorded from both endemic species (including cabbage trees and Scrubwood), native species and introduced species, including Erythrina species. The cloud forest trees have ongoing threats including climate change, and the recent arrival and spread of fungal tree diseases, including Phytophthora spp.. Species of non-native predatory invertebrates living in decaying wood, such as ants, rove beetles, spiders and centipedes, and saproxylic species that modify the dead wood habitat (such as powder-post beetles, millipedes and woodlice) are likely to impact this species negatively. Populations present on non-native plant species are under threat from habitat deterioration and loss from drivers of change including climate change and invasive non-native species. Non-native vertebrate predators, such as rodents and the African Grass Frog (Strongylopus grayi) may also negatively impact this species.

This species is not on the Environmental Protection Ordinance on St Helena, which indicates protected species. However the Peaks are currently within a protected area and part of the government’s Nature Conservation Area (NCAs). This species will benefit from the habitat improvement outlined in the Peaks National Park Management Plan (2019). There is currently no specific action plan for this species, but its conservation and further research will be supported through the St Helena Invertebrate Strategy 2023–2027 (St Helena National Trust and St Helena Government 2023).