True bugs are the largest group within the hemi-metabolous insects, those that develop through incomplete metamorphosis without a pupal stage. More than 45,000 species have been described worldwide, and they are recognised by distinctive anatomical features: a four-segmented labium, a clearly visible triangular scutellum on the back, and forewings called hemelytra that are partly thickened and partly membranous. They occupy aquatic, semi-aquatic and terrestrial habitats and perform a remarkable range of ecological functions, from agricultural pests and vectors of plant diseases to agents of biological control.

Eritrea is an unexpectedly demanding place to survey for such a project. Covering 124,320 square kilometres in north-eastern Africa, the country ranges from 100 metres below sea level in the Danakil Depression, one of the hottest places on Earth, to 3,018 metres at Mount Soyra. The Köppen-Geiger classification places most of the territory in Hot Semi-Arid or Hot Desert climate zones, with mean temperatures between 18 and 35 degrees Celsius and annual rainfall from as little as 50 millimetres along the Red Sea coast to roughly 1,000 millimetres in the eastern escarpment. Yet the country contains four of Africa’s twenty regional centres of vegetation endemism and approximately 430 woody plant species, a botanical foundation that supports a correspondingly diverse insect fauna.

The historical record behind the new checklist is itself a story of colonial science. From 1890 to 1941, during Italy’s colonial administration, Italian naturalists collected extensively across Eritrea. In 1901, Alfredo Andreini worked with the La Specola Zoological Museum in Florence, and Achille Tellini gathered a substantial collection between October 1901 and February 1902 that the Belgian entomologist Henri Schouteden later studied and published. Cesare Mancini described considerable numbers of heteropteran species from specimens collected by Giuseppe Müller, Federico Vaccaro and Marchese Saverio Patrizi, among others. The Finnish entomologist Rauno E. Linnavuori visited Eritrea in May 1963 and published his identifications in an eight-part series covering the Sudan and adjacent countries.

Among the 40 families recorded, Pentatomidae, the stink bugs, is the most diverse with 72 species, accounting for 18.75 percent of the total. Miridae, the plant bugs, follows with 59 species, then Reduviidae, the assassin bugs, with 49, Rhyparochromidae with 35, Coreidae with 22, Lygaeidae with 20 and Cydnidae with 19. The remaining 33 families together account for just over a quarter of recorded species. The dominance of these three leading families reflects their broad ecological adaptability and wide range of feeding strategies, spanning both plant-feeding and predatory habits that allow them to occupy diverse habitats.

The geography of the records is strikingly uneven. Specimens were sampled from more than 50 localities distributed across seven ecoregions, but Asmara alone yielded 115 species, followed by Durfo with 50, Keren and Teseney with 49 each and Ghinda with 45. The Asmara-Massawa roadway, which climbs from sea level to 2,325 metres over 115 kilometres, was sampled for over 350 species records because it was the most accessible and safe route during the twentieth century. The Ethiopian montane grasslands and woodlands ecoregion is the most species-rich with 194 species, nearly a third of the total, followed by Ethiopian montane forests with 147 and Ethiopian xeric grasslands and shrublands with 119. The Eritrean coastal desert ecoregion is virtually unrepresented with a single species, while the East Sudanian savanna produced 60 species from only three localities, suggesting high undiscovered richness.

Habitat preferences follow global patterns. Terrestrial species dominate the Eritrean fauna at 91.43 percent of the total, belonging to 26 families, while aquatic species account for 5.97 percent across seven families and semi-aquatic species make up the remaining 2.60 percent. This distribution mirrors worldwide trends, since only about 10 percent of described Heteroptera species are aquatic or semi-aquatic. The evolutionary origin and early diversification of true bugs were closely associated with terrestrial habitats, and their plant-feeding adaptations allowed them to exploit a wide range of terrestrial resources, while freshwater systems impose stronger physiological and ecological limits on colonisation.

The authorship analysis reveals how concentrated the knowledge base is. Mancini reported 183 species records, Linnavuori 118 and Schouteden 58, meaning the top three contributors account for roughly 63 percent of all species documented. Linnavuori alone authored 25 publications, 18.38 percent of the literature reviewed, followed by Schouteden with 10 and Mancini with five. Publication trends show sparse output before the mid-twentieth century, partly because the world wars mobilised scientists for military service, with 73.53 percent of the 136 reviewed papers produced in the twentieth century and a steady increase from the 1970s onward, particularly in the twenty-first century as researchers study preserved museum specimens.

That museum dependence now exposes a serious gap. Eritrea has experienced a temperature increase of 1.7 degrees Celsius between 1970 and 2014, a general decline in precipitation, an intensification of aridity by roughly 9 percent between 2012 and 2014, and a forest cover decline of more than 50 percent over the same period. Field crops expanded by 52.9 percent and horticultural crops by 346.8 percent between 1992 and 2020, while desertification rose from 38.5 to 66.9 percent of the land surface. Because most heteropterans depend directly on plant communities for food, shelter, diapausing sites and egg-laying locations, these vegetation shifts strongly influence their distribution and abundance. Mirid bugs, in particular, are highly sensitive to synthetic pesticides and ecological disturbance, making them reliable bioindicators of environmental change.

No systematic survey of Eritrean Heteroptera has been conducted for more than 60 years, since Linnavuori’s spring 1963 expedition, a hiatus shaped by Africa’s longest war for independence, which lasted from September 1961 to May 1991, and by the shortage of regional taxonomic experts. The current status of the country’s true bug species remains largely unknown. The study’s authors argue that closing this knowledge gap requires promoting citizen science, training and deploying native professionals, collaborating with international experts, enriching local and regional natural history museum collections and strengthening Eritrean research institutions. They also point to the broader structural imbalance in African taxonomy, where most specimens collected from the continent are stored in museums of the Global North, limiting access for researchers from the Global South, and recommend digitising existing entomological collections and fostering collaboration between professional and amateur entomologists to integrate Eritrea’s diversity into the biogeographical context of north-eastern Africa.

Subject of Research: Heteroptera fauna of Eritrea

Article Title: Heteroptera ( Insecta , Hemiptera ) fauna of Eritrea

Article References: Brhane, D., Kukorellyné Szénási, Á., & Kóbor, P. (2026). Heteroptera (Insecta, Hemiptera) fauna of Eritrea. African Invertebrates, 67(2), 189-232. https://doi.org/10.3897/afrinvertebr.67.192912

Image Credits: AI Generated

DOI: 10.3897/AfrInvertebr.67.192912

Keywords: Heteroptera, Eritrea, entomology, biodiversity, taxonomy, African Invertebrates, true bugs, biogeography, Insecta, Hemiptera, fauna, scientific research