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Insect stings and envenomation

ISSN 2398-2942

Synonym(s): Bee stings, Wasp stings, Insect stings and Venomous insects


  • Venoms are poisonous substances that certain animals can inject by means of a bite, sting or other sharp body feature.
  • Many animals can be described as venomous; these include a wide range of invertebrates and certain fish and reptiles.
  • Amongst the invertebrates, we find spiders, centipedes, scorpions and a wide range of stinging insects. This article deals specifically with venomous insects and focuses particularly on the Hymenoptera.
  • The Hymenoptera, or wasp, order is a very large order containing sawflies and a wide range of parasitic insects as well as bees, wasps, hornets and ants. Most bees and wasps are solitary insects, each living and fending for itself. Ants, bumble bees, honeybees and some wasps are social insects, however. As such, they live in colonies ruled by one or more large female queens, and all work together for the good of the colony.
  • In the UK, the common wasp (Vespula vulgaris) and the honeybee (Apis mellifera) are almost certainly the most common insects likely to sting companion animals.
  • Ants may also "bite" (or "sting") pets Skin: external parasite bite reaction.
  • In the south-eastern United States, the most common culprit responsible for insect stings is probably the Imported Fire Ant (Solenopsis invicta). Print off the Factsheet on Insect stings to give to your client.

Presenting signs

  • Restlessness, pain, swelling, redness, pruritus, localized irritation.

Acute presentation

Geographic incidence

  • Bees and their cousins, the bumblebees, wasps, hornets and ants are found throughout the United Kingdom and in most countries.
  • They are usually not active at temperatures below 13°C (55°F) or on rainy days. The highest incidence of stings is therefore typically in August.

Breed/Species predisposition

  • Inquisitive breeds and individuals may investigate, and/or catch, insects and may perhaps be more predisposed to being stung.

Public health considerations

  • Public health considerations are minimal. Where a bee or wasp nest is found and disturbed within the home and garden there may be some risk to humans, particularly if hypersensitized individuals are exposed.

Cost considerations

  • Cost considerations are minimal in most cases, but hospitalization may be prolonged in animals that develop systemic signs following insect envenomation.

Special risks

  • Oropharyngeal edema, where present, may compromise respiration and make intubation difficult.



  • Female bees and their cousins, the bumblebees, wasps, hornets and ants, do not usually sting unless stepped on, touched, or molested.
  • The poison gland system of the bee consists of a small alkaline gland and a larger acid gland. In the bee the venom is produced by these two glands, which are associated with the ovipositor (egg-laying organ) of the female. The stinger is made up of two lancets with sharp barbs pointing backward, similar to a harpoon. This distinction is important because it means that the sting of a bee will usually remain implanted in the skin of the individual that has been stung. In doing so, it will tear away from the bee's abdomen, leading to the death of the bee. The stinger left behind by the bee can continue to inject venom into the tissues.
  • Wasps and hornets, by contrast, have smooth stingers and are therefore able to retain their stingers.
  • Massive venom attacks occur in the Americas from so called Africanized or killer bees (Apis mellifera scutellata).  These are descendants of African bees that escaped from a research facility in Brazil in 1957 and hybridized with local bees.  The venom of Africanised bees is similar to that of domesticated honeybee, but the bees are more aggressive and the risk of multiple stings is far greater.  They are stimulated to an aggressive state quicker than other bees and will pursue for a long distance.
  • The Imported Fire Ant can be very aggressive if their nest is disturbed.

Predisposing factors


  • Contact with bees, wasps and other stinging insects.


  • Insects are attracted to flower fragrances, bright colors against dark backgrounds as well as sugary foods.
  • Bees and wasps tend to frequent clover fields, orchards, picnic sites and dustbins.
  • Certain insects, including the Imported Fire Ant, are aggressive if their nest is disturbed.


  • Bee venom is a very complicated substance with several active biochemical components.
  • At least eight active components plus several biological inactive components have been identified. The substances showing activity are histamine, melittin (a protein), a hyaluronidase, and phospholipase A.
  • The histamine is not thought to be a pharmacological factor in bee venom. Histamine can, however, be released in allergic individuals in response to the sting.
  • The protein, melittin, is thought to be responsible for the general local toxicity of the venom and, at high concentrations, can cause hemolysis of red blood cells.
  • Bee venom contains at least two enzymes, including a hyaluronidase and phospholipase A. Hyaluronidase facilitates venom infiltration through the tissues. Phospholipase A causes inactivation of thrombokinase, inhibits oxidative phosphorylation, and attacks enzymes involved with metabolic dehydrogenation. The pain experienced after being stung may well be the result of these last three actions.
  • Wasp venom also contains the enzymes hyaluronidase and phospholipase A.
  • Sensitization to insect venom can occur after a single sting.
  • The most allergenic component of wasp venom is a protein called Antigen 5 (or Ves g V). The most allergenic component of bee venom is the enzyme phospholipase. The hyaluronidase enzymes present in both bee and wasp venom may result in cross reaction allergy but the incidence of this in dogs is uncertain.
  • The bulk of Imported Fire Ant venom consists of piperidine alkaloids. These are present in a non-protein, non-polar alkaline phase. The alkaloids are cytotoxic and are responsible for the severe inflammatory response.
  • Formic acid, produced by ants, has a pH of 2-3 and is therefore markedly acidic.


  • Non allergic reactions may develop over a period of up to several hours and resolve over the following few days.
  • Allergic reactions in sensitized individuals may develop within 10 minutes of a sting.


  • As in humans, life threatening reactions are more likely to occur in highly allergic individuals, elderly patients with pre-existing cardiac or respiratory diseases or in multiple stings.
  • Stings to the face, neck and head are more likely to trigger anaphylaxis.


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Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Nair R, Riddle E A & Thrall M A (2019) Hemolytic anemia, spherocytosis, and thrombocytopenia associated with honey bee envenomation in a dog. Vet Clin Pathol 48 (4), 620-623 PubMed.
  • Mughal M N, Abbas G, Saqib M & Muhammad G (2014) Massive attack by honeybees in a German shepherd dog: description of a fatal case and review of the literature. J Venom Anim Toxins Incl Trop Dis 20 (1), 55 PubMed.
  • Niza M E et al (2012) Effects of Pine Processionary Caterpillar Thaumetopoea pityocampa Contact in Dogs: 41 cases (2002-2006). Zoonoses and Public Health 59 (1), 35-38 PubMed.
  • Oliveira E C, Pedroso P M, Meirelles A E et al (2007) Pathological findings in dogs after multiple Africanized bee stings. Toxi. 49 (8), 1214-1218 PubMed.
  • Fitzgerald K T & Flood A A (2006) Hymenoptera stings. Clin Tech Small Anim Pract 21 (4), 194-204 PubMed.
  • Walker T, Tidwell A S, Rozanski E et al (2005) Imaging diagnosis: acute lung injury following massive bee envenomation in a dog. Vet Radiol Ultrasound 46 (4), 300-303 PubMed.
  • Shimada A, Nakai T, Sawada M et al (2005) Systemic rhabdomyonecrosis and acute tubular necrosis in a dog associated with wasp stings. Vet Rec 156 (10), 320-322 PubMed.
  • Wojcik D P, Allen C R, Brenner R J et al (2001) Red Imported Fire Ants: Impact on biodiversity. American Entomologist 47 (1), 16-23 Oxford Academic.
  • Noble S J & Armstrong P J (1999) Bee sting envenomation resulting in secondary immune-mediated hemolytic anemia in two dogs. J Am Vet Med Assoc 214 (7), 1026-1027 PubMed.
  • Waddell L S & Drobatz K J (1999) Massive envenomation by Vespula spp in two dogs. J Vet Emerg Crit Care (2), 67-71 VetMedResource.
  • Friberg C A & Lewis D T (1998) Insect hypersensitivity in small animals. Comp Contin Educ Pract Vet 20 (10), 1121-1131 VetMedResource.
  • Jemal A & Hugh-Jones M (1993) A review of the red imported fireant (Solenopsis invicta Buren) and its impacts on plant, animal, and human health. Prev Vet Med 17 (1-2), 19-32 ScienceDirect.

Other sources of information

  • Cohen, R. (1995) Systemic Anaphylaxis.In: Current Veterinary Therapy XII. Small Animal Practice. Ed: Bonagura J. W.B. Saunders, USA.


  • ASPCA Animal Poison Control Center. Tel: +1 (888) 426-4435. Website:
  • Veterinary Poisons Information Service (VPIS): Tel: +44 (0) 2073 055 055. Website: