ISSN 2398-2969      

Insect stings and envenomation


Glen Cousquer


  • 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 theHymenoptera.
  • The Hymenoptera, or wasp, order is a very large order containing the sawflies and a wide range of parasitic insects as well as the bees, wasps, hornets and ants. Most bees and wasps are solitary insects, each living and fending for itself. Ants, bumble bees, honey bees 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 honey bee (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 southeastern United States, the most common culprit responsible for insect stings is probably the Imported Fire Ant (Solenopsis invicta).
  • Many caterpillars also have defensive venom glands. These are associated with specialized bristles, known as urticating hairs.
    Print off the owner factsheet Insect stings Insect stings to give to your client.



  • 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 for 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 bees 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.
  • The Imported Fire Ant can be very aggressive if their nest is disturbed (Wojciket al, 2001).

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.
  • Urticarial caterpillars may be encountered when holidaying in continental Europe.


  • Bee venom is a very complicated substance with several active bio chemical 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.


  • 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.
  • 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.
  • Fitzgerald K T & Flood A A (2006) Hymenoptera stings. Clin Tech Small Anim Pract 21 (4), 194-204 PubMed.
  • Shimada A, Nakai T, Sawada M, Uemura T & Haruna A (2005) Systemic rhabdomyonecrosis and acute tubular necrosis in a dog associated with wasp stings. Vet Rec 156 (10), 320-322 PubMed.
  • Wojcik D P 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. Compend 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. Preventative Veterinary Medicine 17 (1-2), 19-32 ScienceDirect.

Other sources of information

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


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