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Lethocerus delpontei, one of the largest species of giant water bugs. The insect pictured was responsible for the bite in case 6.  

Lethocerus delpontei, one of the largest species of giant water bugs. The insect pictured was responsible for the bite in case 6.  

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We report 7 cases of patients bitten by giant water bugs, large predatory insects belonging to the Belostomatidae family (Hemiptera, Heteroptera). These insects have toxic saliva capable of provoking intense pain and paralysis in vertebrates. Victims experienced intense, excruciating pain and 1 manifested hypoesthesia in the forearm. Bites by Belos...

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... giant water bugs can be quite large; those from the genus Lethocerus can reach more than 12 cm in length. The main Lethocerus species in Brazil are L delpontei, L grandis, and L maximus ( Figure 1). ...

Citations

... Predaceous heteropterans can harm humans and animals by causing pain, tissue necrosis, numbness, respiratory disturbances, and death (Walker et al., 2016). Severe pain and local anesthesia have been reported by victims bitten by giant water bugs, implying high toxicity of the venom of this predaceous heteropteran (Haddad et al., 2010). ...
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Salivary gland-specific transcriptomes of nine heteropteran insects with distinct feeding strategies (predaceous, hematophagous, and phytophagous) were analyzed and annotated to compare and identify the venom components as well as their expression profiles. The transcriptional abundance of venom genes was verified via quantitative real-time PCR. Hierarchical clustering of 30 representative differentially expressed venom genes from the nine heteropteran species revealed unique groups of salivary gland-specific genes depending on their feeding strategy. The commonly transcribed genes included a paralytic neurotoxin (arginine kinase), digestive enzymes (cathepsin and serine protease), an anti-inflammatory protein (cystatin), hexamerin, and an odorant binding protein. Both predaceous and hematophagous (bed bug) heteropteran species showed relatively higher transcription levels of genes encoding proteins involved in proteolysis and cytolysis, whereas phytophagous heteropterans exhibited little or no expression of these genes, but had a high expression of vitellogenin, a multifunctional allergen. Saliva proteomes from four representative species were also analyzed. All venom proteins identified via saliva proteome analysis were annotated using salivary gland transcriptome data. The proteomic expression profiles of venom proteins were in good agreement with the salivary gland-specific transcriptomic profiles. Our results indicate that profiling of the salivary gland transcriptome provides important information on the composition and evolutionary features of venoms depending on their feeding strategy. This article is protected by copyright. All rights reserved
... FISCHER Et al. venoms are often allergenic and pose a risk of fatal anaphylaxis in humans (Bonifazi et al., 2005;Müller, 2010). In contrast, the suborder Heteroptera has been largely overlooked, although some species can inflict severe defensive bites on humans when disturbed (Haddad, Schwartz, Schwartz, & Carvalho, 2010;dos Santos, de Souza, Zanette, da Silva, & Strussmann, 2019). The Heteroptera are a diverse group of phytophagous, zoophagous, and hematophagous species that have adapted to exploit many terrestrial, aquatic, and semiaquatic habitats (Henry, 2009;Schuh & Weirauch, 2020). ...
... Backswimmers (Notonectidae), also called water bees, occasionally inflict painful bites on humans during swimming (Diaz, 2016). Bites inflicted by assassin bugs and belostomatids are extremely painful, and can trigger various symptoms including edema (Haddad et al., 2010;Hartwig, 1977;dos Santos et al., 2019), paresthesia and pruritus (dos Santos et al., 2019), and pseudoparalysis (Haddad et al., 2010). ...
... Backswimmers (Notonectidae), also called water bees, occasionally inflict painful bites on humans during swimming (Diaz, 2016). Bites inflicted by assassin bugs and belostomatids are extremely painful, and can trigger various symptoms including edema (Haddad et al., 2010;Hartwig, 1977;dos Santos et al., 2019), paresthesia and pruritus (dos Santos et al., 2019), and pseudoparalysis (Haddad et al., 2010). ...
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The Heteroptera are a diverse suborder of phytophagous, hematophagous, and zoophagous insects. The shift to zoophagy can be traced back to the transformation of salivary glands into venom glands, but the venom is used not only to kill and digest invertebrate prey but also as a defense strategy, mainly against vertebrates. In this study, we used an integrated transcriptomics and proteomics approach to compare the composition of venoms from the anterior main gland (AMG) and posterior main gland (PMG) of the reduviid bugs Platymeris biguttatus L. and Psytalla horrida Stål. In both species, the AMG and PMG secreted distinct protein mixtures with few interspecific differences. PMG venom consisted mostly of S1 proteases, redulysins, Ptu1‐like peptides, and uncharacterized proteins, whereas AMG venom contained hemolysins and cystatins. There was a remarkable difference in biological activity between the AMG and PMG venoms, with only PMG venom conferring digestive, neurotoxic, hemolytic, antibacterial, and cytotoxic effects. Proteomic analysis of venom samples revealed the context‐dependent use of AMG and PMG venom. Although both species secreted PMG venom alone to overwhelm their prey and facilitate digestion, the deployment of defensive venom was species‐dependent. P. biguttatus almost exclusively used PMG venom for defense, whereas P. horrida secreted PMG venom in response to mild harassment but AMG venom in response to more intense harassment. This intriguing context‐dependent use of defensive venom indicates that future research should focus on species‐dependent differences in venom composition and defense strategies among predatory Heteroptera.
... En el caso de los integrantes de la familia Cimicidae, pueden alimentarse primordialmente sobre Aves y Quirópteros, y algunas especies sobre humanos, ya sea de forma facultativa u obligatoria (Tabla 1); las especies Cimex lectularius (L.) y Cimex hemipterus (F.) se adaptaron exclusivamente a parasitar a los humanos, siendo los agentes causantes de cimicosis, y se les denomina comúnmente como "chinches de cama" (bed bugs), debido a que habitan en colchones y muebles y pican a los humanos con mayor énfasis durante la noche; las manifestaciones clínicas debido a sus picaduras pueden causar desde pequeñas pápulas eritematosas con un leve prurito, hasta lesiones más severas (pápulo edematosas, máculas) con prurito intenso y sensación de quemadura (urticaria cimicina), con un constante rascado por parte del paciente; esto puede conllevar a la aparición de infecciones bacterianas secundarias, además de, entre otros problemas, insomnio, fatiga, alucinaciones, pesadillas, depresión, asma, shock anafiláctico, anemia. A pesar de que en la saliva, tracto digestivo y heces de estos "chinches de cama" se han detectado varios tipos de agentes patógenos, aún no se ha demostrado que puedan multiplicarse en los mismos y transmitirlos al humano (Stiles y Hassall 1928, Ryckman 1979, O'Donel 1984, Kadlec et al. 1996, Robinson 2005 Los demás grupos de heterópteros (fitófagos y depredadores) también pueden presentar importancia sanitaria (Tabla 1), ya sea porque invanden la vivienda humana y son una molestia en sí mismos por sus ingentes poblaciones; o porque emiten líquidos apestosos e irritantes a nivel cutáneo (dermatitis) u ocular (queratitis), u ocasionan picaduras, las cuales son adventicias, y pudieran deberse a una acción defensiva o a la búsqueda de agua y/o solutos; asimismo, en algunos individuos susceptibles, estos insectos pueden provocar reacciones alérgicas (Schaefer 2000, 2003, Haddad Jr. et al. 2002, Anderson et al. 2012, Faúndez 2016, 2020, Haddad Jr. et al. 2010, 2015, Faúndez y Rojas-Porras 2016, Shen y Hu 2017, Faúndez et al. 2019, Faúndez 2020. ...
... Belostomatidae, Corixidae, Naucoridae, Nepidae y Notonectidae (Tabla 1); varias especies de las mismas son de gran tamaño y capaces de ocasionar envenenamientos con picadas muy dolorosas con sus estiletes mandibulares y maxilares a las personas en los ambientes acuáticos/semiácuáticos; además de edema, parestesia y pseudoparálisis de la región anatómica afectada y en algunos casos disnea, dolor abdominal, fiebre y sensación de constricción de la faringe, pudiendo inyectarles su saliva que posee enzimas proteolíticas, esteroides (pregnanos) y lisofosfolípidos; probablemente pudieran transmitir agentes infecciosos como la micobacteria Mycobacterium ulcerans (MacCallum et al. 1948), agente etiológico de la úlcera de Buruli, enfermedad ulcerativa extensa; esto debido a que se ha aislado esta micobacteria de sus glándulas salivares (Huntley 1998, Díaz y Péfaur 2006, Mosi et al. 2008, Kazda et al. 2009, Cupul-Magaña 2012, Haddad Jr. et al. 2010, 2015, Carolan et al. 2014, Díaz 2016, Faúndez y Rojas-Porras 2016, Cano et al. 2018, Faúndez 2020. Mientras que dentro de los heterópteros que son depredadores terrestres, se incluyen taxones de las familias Anthocoridae, Lyctocoridae, Nabidae, Pachynomidae, Pentatomidae (Asopinae) y Reduviidae (Tabla 1), varias de las cuales ocasionan picadas también dolorosas y algunos pacientes muestran similares manifestaciones clínicas a las ya mencionadas (Stiles y Hassall 1928, Myers 1929, Usinger 1934, Roberts y Knowlton 1951, Wray 1971, Cook y Lee 1977, Hartwig 1977, Hunt 1977, Ryckman 1979, Ryckman y Bentley 1979, Leclercq y Verstraeten 1982, O'Donel 1984, Jones et al. 1988, Atkinson 1990, Kadlec et al. 1996, Robinson 2005 Aparece significativo señalar que a pesar de sus efectos negativos para la salud humana, algunos taxones de hemípteros-heterópteros se les emplean como agentes terapéuticos en la medicina tradicional China (Meyer-Rochow 2017, Seabrooks y Hua 2017). ...
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RESUMEN Los heterópteros (Heteroptera) o "chinches verdaderos" son insectos del orden Hemiptera que poseen un aparato bucal picador-chupador con hábitos alimentarios muy variados, incluyendo fitofagia en la mayoría de las especies, hemolinfagia (zoofagia, entomofagia) y hematofagia. Varios taxones de heterópteros pueden causar molestias o daños al ser humano, ya sea mediante picaduras adventicias de especies fitófagas o zoófagas, o transmitiendo agentes patógenos y/o provocando potencialmente shock anafilácticos severos de especies con hematofagia obligatoria. Por ello, se presentan comentarios y se revisa la literatura científica acerca de la importancia sanitaria de los hemípteros-heterópteros. ABSTRACT Heteropterans (Heteroptera) or "true bugs" are insects in the order Hemiptera that possess piercing-sucking mouthparts with a wide variety of feeding habits, including phytophagy in most of species, hemolymphagy (zoophagy, entomophagy) and hematophagy. Several heteropteran taxa can be a nuisance to humans, either through adventitious bites of phytophagous and zoophagous species, or transmitting pathogens and/or potentially causing severe anaphylactic shock from species with obligatory hematophagy. Thus, comments are presented and a scientific literature review is made about the sanitary relevance of hemiptera-heteropteran insects.
... Belostomatidae (giant water bugs) 169 sp.: They are general predators and feed on aquatic invertebrates and vertebrates (amphibians, fishes, turtles, birds), which are captured with their raptorial forelegs and quickly immobilized with the poisonous secretion from the salivary glands (de Carlo et al. 1973). The bites which are very painful for humans also represent effective defense mechanisms (Haddad et al. 2010). The belostomatid saliva reveals proteins from 5 to 55 kDa (Walker et al. 2016). ...
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This chapter compiles active and passive defensive mechanisms of aquatic and semiaquatic developmental stages of all insect orders against various predators. Mainly escape reactions, mechanical defense, defensive stridulation, and especially chemical defenses are described, illustrated, and tabulated. Apart from the large aquatic groups of ephemeropteran, Odonata or Trichoptera larvae especially aquatic bugs and water beetles are considered by even including small groups from Collembola up to Mecoptera. Differences between defensive mechanisms and strategies in aquatic and terrestrial insects are described. Aquatic insects especially rely on escape, mechanical defenses, defensive stridulation, and chemical defenses. Exocrine glands are mainly restricted to large taxa with both terrestrial and aquatic representatives (adephagan beetles, Heteroptera) and not invented in aquatic groups. Chemically aquatic insects especially evolved biosynthesis of aromatic and few aliphatic compounds against microorganisms. In contrast mainly steroids are targeted against cold-blooded vertebrates such as fishes and amphibians. As compared with terrestrial insects, aquatic representatives lack many mechanisms of defense such as reflex bleeding, incorporation of toxic compounds from plants, freshwater animals, or microorganisms. Exocrine secretions of water insects are usually externalized by secretion grooming in order to receive a clean body surface, to achieve an optimal breathing, and to modify the wettability of the body surface. Generally there exists a considerable lack of knowledge concerning bionomy and especially defenses of aquatic insects.
... Some venom proteins of predaceous heteropterans are likely to have been unnecessary and possibly disadvantageous when applied to other trophic strategies. For example, venoms of belostomatids and predatory reduviids induce strong pain sensations when injected into vertebrates [55,56], whereas the venom of blood-feeding reduviids has an analgesic effect [57]. Blood-feeding reduviids have likely undergone active selection to lose pain-causing molecules from their venom to evade host detection, accompanying their transition to haematophagy 24-38 mya [58]. ...
Article
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True Bugs (Insecta: Heteroptera) produce venom or saliva with diverse bioactivities depending on their feeding strategies. However, little is known about the molecular evolution of the venom toxins underlying these biological activities. We examined venom of the giant fish-killing water bug Lethocerus distinctifemur (Insecta: Belostomatidae) using infrared spectroscopy, transcriptomics, and proteomics. We report 132 venom proteins including putative enzymes, cytolytic toxins, and antimicrobial peptides. Over 73% (96 proteins) showed homology to venom proteins from assassin bugs (Reduviidae), including 21% (28 proteins from seven families) not known from other sources. These data suggest that numerous protein families were recruited into venom and diversified rapidly following the switch from phytophagy to predation by ancestral heteropterans, and then were retained over > 200 my of evolution. In contrast, trophic switches to blood-feeding (e.g. in Triatominae and Cimicidae) or reversions to plant-feeding (e.g., in Pentatomomorpha) were accompanied by rapid changes in the composition of venom/saliva, including the loss of many protein families.
... Many families of venom proteins are found in both Reduviidae and Belostomatidae, which span much or all of the phylogenetic diversity in Heteroptera, leading us to propose that many of these were recruited into venom anciently in heteropteran evolution (Walker et al., 2018a). Heteropteran venoms are known to cause paralysis, tissue liquefaction and death when injected into invertebrates (Edwards, 1961;Zerachia et al., 1973a;Maran and Ambrose, 2000;Maran et al., 2011;Walker et al., 2018b), and pain and sometimes neurotoxic symptoms and/or death when injected into vertebrates (Zerachia et al., 1973a;Haddad et al., 2010). Assassin bug venom is also known to have a strong cytolytic effect on both insect and mammal cells (Edwards, 1961; (Mansell, 1999). ...
Article
The insects are a hyperdiverse class containing more species than all other animal groups combined-many of which employ venom to capture prey, deter predators and micro-organisms, or facilitate parasitism or extra-oral digestion. However, with the exception of those made by Hymenoptera (wasps, ants and bees), little is known about insect venoms. Here, we review the current literature on insects that use venom for prey capture and predator deterrence, finding evidence for fourteen independent origins of venom usage among insects, mostly among the hyperdiverse holometabolan orders. Many lineages, including the True Bugs (Heteroptera), robber flies (Asilidae), and larvae of many Neuroptera, Coleoptera and Diptera, use mouthpart-associated venoms to paralyse and pre-digest prey during hunting. In contrast, some Hymenoptera and larval Lepidoptera, and one species of beetle, use non-mouthpart structures to inject venom in order to cause pain to deter potential predators. Several recently published insect venom proteomes indicate molecular convergence between insects and other venomous animal groups, with all insect venoms studied so far being potently bioactive cocktails containing both peptides and larger proteins, including novel peptide and protein families. This review summarises the current state of the field of entomo-venomics.
... Kissing bugs (Reduviidae: Triatominae) bite vertebrates (including humans) to feed on their blood; in the process they spread trypanosomes responsible for Chagas disease-a condition that results in more than 7000 deaths per year and substantial diminution in quality of life for affected individuals [3]-and cause allergic responses including anaphylaxis [4]. Predaceous heteropterans such as assassin bugs (Reduviidae) and backswimmers (also known as water bees, Notonectidae) may bite humans, causing pain, tissue necrosis, numbness, respiratory disturbances, and in extreme cases, death [5][6][7][8][9]. While some plant-feeding heteropterans are agricultural pests that incur billions of dollars in management costs annually, others are valued biocontrol agents in agricultural ecosystems [1,10]. ...
... Most information regarding the venoms of the water-associated groups is from Belostomatidae, Nepidae and Notonectidae, while essentially nothing has been recorded of the venoms of Gerromorpha or Leptopodomorpha. Humans bitten by aquatic water bugs experience pronounced pain, swelling, vasodilation and sometimes numbness [7] while invertebrates and small vertebrates bitten by belostomatids or injected with their venom are typically paralysed after several minutes [24,68]. Venom gland extracts equivalent to 1% of the glands of the creeping water bug Naucoris cimicoides dissolved in 100 µL saline result in immediate cessation of beating of the cockroach heart-dorsum preparation [6]. ...
Article
Heteropteran insects such as assassin bugs (Reduviidae) and giant water bugs (Belostomatidae) descended from a common predaceous and venomous ancestor, and the majority of extant heteropterans retain this trophic strategy. Some heteropterans have transitioned to feeding on vertebrate blood (such as the kissing bugs, Triatominae; and bed bugs, Cimicidae) while others have reverted to feeding on plants (most Pentatomomorpha). However, with the exception of saliva used by kissing bugs to facilitate blood-feeding, little is known about heteropteran venoms compared to the venoms of spiders, scorpions and snakes. One obstacle to the characterization of heteropteran venom toxins is the structure and function of the venom/labial glands, which are both morphologically complex and perform multiple biological roles (defense, prey capture, and extra-oral digestion). In this article, we describe three methods we have successfully used to collect heteropteran venoms. First, we present electrostimulation as a convenient way to collect venom that is often lethal when injected into prey animals, and which obviates contamination by glandular tissue. Second, we show that gentle harassment of animals is sufficient to produce venom extrusion from the proboscis and/or venom spitting in some groups of heteropterans. Third, we describe methods to harvest venom toxins by dissection of anaesthetized animals to obtain the venom glands. This method is complementary to other methods, as it may allow harvesting of toxins from taxa in which electrostimulation and harassment are ineffective. These protocols will enable researchers to harvest toxins from heteropteran insects for structure-function characterization and possible applications in medicine and agriculture.
... Giant water bugs in the genus Lethocerus are the largest Asian Heteroptera (Perez Goodwyn, 2006). As nocturnal aquatic predators, they inhabit rice fields, ponds, lakes, ditches and slow-running rivers and streams (Kopelke, 1982;Yoon et al., 2010;Haddad et al., 2010;Choate, 2011;Vũ & Lê, 2012). The observation of Lethocerus cf. ...
... Besides consuming a wide range of aquatic invertebrates and small fish, giant water bugs prey on amphibians (Kopelke, 1982;Kwet & Schlüter, 2002;Bernard, 2007;Ohba, 2011b) which they kill and digest with their saliva (Haddad et al., 2010). While mature specimens eat full-grown frogs, nymphs prefer tadpoles (Ohba, 2011a). ...
Article
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A biodiversity survey was conducted in spring 2012 in eastern Chu Mom Ray National Park, Kon Tum Province, central Vietnam, to identify and record predaceous arthropod taxa that are known to include reptile and amphibian prey in their diet as well as those of large body size (>= 60 mm). Five drift fence arrays with pitfalls and double-ended funnel traps were installed in lowland ever-green forest and monitored over 40 nights. Additionally, 22 nocturnal searches were conducted along an adjacent forest stream. Recorded large arthropod predators comprise of one Asian forest scorpion species (Heterometrus petersii), at least three different tarantula species in the subfamily Selenocosmiinae, one scolopendromorph centipede species (Scolopendra dehaani), one scutigero-morph centipede (Thereuopoda longicornis), one giant water bug species (Lethocerus cf. indicus), one creeping water bug species in the family Naucoridae, two water scorpion species (Cercotmetus sp. and Laccotrephes sp.), one species of army ant (Aenictus sp.), four species of praying mantises (Hierodula fruhstorferi, Hierodula patellifera, Tenodera aridifolia and Theopropus elegans) and one species of freshwater crab (Balssipotamon fruhstorferi). In two cases, the predation of Aenictus sp. on the caecilian Ichthyophis cf. nguyenorum was observed. Conservation measures for giant water bugs, tarantulas and Asian forest scorpions are discussed. Key words: Arthropods, predators, herpetofauna, biodiversity survey, conservation.
... Hemipteran insect, Lethocerus indicus of the family, Belostomatidae produces toxic saliva capable of provoking intense pain and paralysis in vertebrates including human [1][2]The venom is a secretion produced in a specialized gland in one animal and delivered to a target animal through inflicting a wound that causes disruption in normal physiological processes [3]. The salivary venom of L. indicus is used as an anti tumour medicine by the traditional healers since long back [4]. ...
... Kissing bugs (Reduviidae: Triatominae) bite vertebrates (including humans) to feed on their blood; in the process they spread trypanosomes responsible for Chagas disease-a condition that results in more than 7000 deaths per year and substantial diminution in quality of life for affected individuals [3]-and cause allergic responses including anaphylaxis [4]. Predaceous heteropterans such as assassin bugs (Reduviidae) and backswimmers (also known as water bees, Notonectidae) may bite humans, causing pain, tissue necrosis, numbness, respiratory disturbances, and in extreme cases, death [5][6][7][8][9]. While some plantfeeding heteropterans are agricultural pests that incur billions of dollars in management costs annually, others are valued biocontrol agents in agricultural ecosystems [1,10]. ...
... Kissing bugs (Reduviidae: Triatominae) bite vertebrates (including humans) to feed on their blood; in the process they spread trypanosomes responsible for Chagas disease-a condition that results in more than 7000 deaths per year and substantial diminution in quality of life for affected individuals [3]-and cause allergic responses including anaphylaxis [4]. Predaceous heteropterans such as assassin bugs (Reduviidae) and backswimmers (also known as water bees, Notonectidae) may bite humans, causing pain, tissue necrosis, numbness, respiratory disturbances, and in extreme cases, death [5][6][7][8][9]. While some plant-feeding heteropterans are agricultural pests that incur billions of dollars in management costs annually, others are valued biocontrol agents in agricultural ecosystems [1,10]. ...
... Most information regarding the venoms of the water-associated groups is from Belostomatidae, Nepidae and Notonectidae, while essentially nothing has been recorded of the venoms of Gerromorpha or Leptopodomorpha. Humans bitten by aquatic water bugs experience pronounced pain, swelling, vasodilation and sometimes numbness [7] while invertebrates and small vertebrates bitten by belostomatids or injected with their venom are typically paralysed after several minutes [24,68]. Venom gland extracts equivalent to 1% of the glands of the creeping water bug Naucoris cimicoides dissolved in 100 µL saline result in immediate cessation of beating of the cockroach heart-dorsum preparation [6]. ...
Article
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The piercing-sucking mouthparts of the true bugs (Insecta: Hemiptera: Heteroptera) have allowed diversification from a plant-feeding ancestor into a wide range of trophic strategies that include predation and blood-feeding. Crucial to the success of each of these strategies is the injection of venom. Here we review the current state of knowledge with regard to heteropteran venoms. Predaceous species produce venoms that induce rapid paralysis and liquefaction. These venoms are powerfully insecticidal, and may cause paralysis or death when injected into vertebrates. Disulfide-rich peptides, bioactive phospholipids, small molecules such as N,N-dimethylaniline and 1,2,5-trithiepane, and toxic enzymes such as phospholipase A2, have been reported in predatory venoms. However, the detailed composition and molecular targets of predatory venoms are largely unknown. In contrast, recent research into blood-feeding heteropterans has revealed the structure and function of many protein and non-protein components that facilitate acquisition of blood meals. Blood-feeding venoms lack paralytic or liquefying activity but instead are cocktails of pharmacological modulators that disable the host haemostatic systems simultaneously at multiple points. The multiple ways venom is used by heteropterans suggests that further study will reveal heteropteran venom components with a wide range of bioactivities that may be recruited for use as bioinsecticides, human therapeutics, and pharmacological tools.