Blister beetles, insects of taxonomic family Meloidae, are categorized in 120 different genera and thousands of species. With physical contact, blister beetles are capable of bringing upon blisters in humans, hence their descriptive common moniker. They're also sometimes referred to as oil beetles, specifically those from the subfamily Meloinae.
Number of Species
The world of blister beetles is vast. Roughly 2,500 species of these beetles are known. They are common throughout many regions of the United States. The mainland United States hosts no fewer than 300 species of them. Texas alone is home to a minimum of 100 blister beetle species. Florida is home to 26.
The 2,500 species of blister beetles are divided across four subfamilies. These subfamilies are Eleticinae, Meloinae, Tetraonycinae and Nemognathinae. Eleticinae is often considered to be the most primordial of all of the Meloidae subfamilies. Blister beetles of this subfamily are common in eastern Asia and in regions of Africa. Meloinae beetles are seen in many areas of the planet, bar Australia. Tetraonycinae beetles are prevalent in the Americas. Nemognathinae blister beetles, which often possess lengthy maxillae, are commonly seen in Australia.
Some of the many species of blister beetles found throughout the United States are the striped blister beetle (Epicauta vittata), the black blister beetle (Epicauta pennsylvanica) and the ashgray blister beetle (Epicauta fabricii). Depending on species, blister beetle species look somewhat different, notably in the color and form departments. Some are darker or lighter than others; some are shorter or longer than other varieties.
Despite differences that exist between the species of blister beetles, mature specimens typically grow to between three-eighths of an inch to a full inch in length. Some of them are black in coloration, while others are purely gray or brown. They're occasionally even greenish-blue or green. Some have streaks or specks in white, black, yellow, orange, brown or red. They generally have elongated and slender, cylindrical physiques. Blister beetles' heads are typically markedly broader than their pronota. Their bodies are generally somewhat soft and smooth in texture. Their limbs have lengthy appearances. Visually, blister beetles are often compared to darkling beetles, checkered beetles and tiger beetle, among others.
Cantharidin in Blister Beetles
Blister beetles' bodies consist of cantharidin. This poisonous and greasy chemical assists them in keeping safe from others. If a blister beetle's body gets smashed by a human for whatever reason, it could lead to the emergence of an uncomfortable blister. As far as levels of cantharidin go, blister beetles run the gamut. Some species have much more significant amounts than others. Not only is cantharidin hazardous to human beings, it also is a risk to animals such as horses. Horses that have experienced the toxicity of these beetles have even passed away. This is common in horses who consume hay that has been exposed to the poison. When horses consume the poison in considerable amounts, a handful of other effects are possible along with fatalities, specifically shock and fever. Cows and sheep have also died from blister beetle poisoning.
- University of Florida IFAS Extension: Blister Beetles
- Texas A&M AgriLife Extension: Blister Beetle
- University of Kentucky Entomology: Blister Beetles in Alfalfa
- University of Illinois Extension & Outreach: Blister Beetles
- New Mexico State University Cooperative Extension Service: Beetle Blisters in Alfalfa
- Montana State University Extension: Blister Beetles of Montana
- Colorado State University Extension: Blister Beetles in Forage Crops
- Cambridge University Press: A Classification of the Genera and Higher Taxa of the Meloid Subfamily Eleticinae
- Australian Beetles Volume 1; John Lawrence and Adam Slipinski
- USDA: The Systematics and Biology of Blister Beetles