Beetles are some of the most fascinating animals on the planet. Green iridescent beetles, in particular, have piqued the curiosity of anyone who has chanced upon them outdoors. This article explores some of these amazing insects.
As the largest in the insect class, the order Coleoptera includes over 350,000 species. Along with weevils, these insects are collectively more commonly known as beetles.
It would be pretty much impossible to cover such an incredibly diverse order in a single list. Instead, this article aims to give you a glimpse into the fascinating world of beetles through some of its most eye-catching representatives: green iridescent beetles.
These shiny, metallic beetles are often confused for one another due to their signature hue, but in truth, they are practically as diverse as the order they belong to. Let’s take a closer look at some of these fascinating creatures.
Types of Green Iridescent Beetles
1. Mint Leaf Beetle (Chrysolina herbacea)
The mint leaf beetle starts life out as a fat black larva before developing its distinct color in adulthood. Mature mint leaf beetles’ green iridescence can often catch copper, purple, or blue in the light.
As the name suggests, both larvae and adults subsist mainly on a diet of various mint plants, leaving tears and holes in the leaves. However, they have also been found feeding on other aromatics such as basil thyme.
The mint leaf beetle is perhaps one of the most geographically common species among green iridescent beetles. While it is most common in central Southern England, it can also be found in Germany, Italy, and Portugal, in western Central Asia, the Caucasus, and Turkey.
2. Willow Flea Beetle (Crepidodera aurata)
Another geographically widespread green iridescent beetle is the Crepidodera aurata, or the willow flea beetle. These beetles can be found all across the Palearctic, to parts of the Middle East and West Africa, to Europe and the UK. These tiny (only 2.5-3mm long) creatures have proven to be quite an adaptable species, able to exist anywhere from lowlands to as high as 1500m altitudes in Bulgaria. As long as host willow trees can be found, willow flea beetles can also be spotted.
Willow flea beetles may share the same shiny green color as the other insects on the list, but there is an easy way to identify them. While they are predominantly metallic green, they are distinctly bicolored, with a reddish bronze head.
3. Golden Ground Beetle (Carabus auratus)
The Carabus auratus is among the bigger species of green iridescent beetles. Better known as the golden ground beetle, it can average up to 20-27mm long! Its head, thorax, and abdomen bear an entirely bright green or coppery-green sheen, while the legs, antennae, and mouthparts are orange. Another distinguishing feature of these large insects is the presence of long grooves or ridges running down their elytra.
Originally, these beetles were native to Central and Western Europe. They were only introduced to North America in the 1940s as a natural means to counter the proliferation of brown-tail and gypsy moths. Due to a combination of natural dispersion, human transport of agricultural products, and highway construction through its grassland habitats, ground beetle populations have since spread. In 2013, a first sighting was recorded in Canada.
4. Green Dock Beetle (Gastrophysa viridula)
Unlike other beetles on the list that are bicolored or bear distinguishing marks of a different color, the green dock beetle is entirely green, including its appendages. It is also is one of the more “jewel-like” iridescent beetles, with its elytra catching the light in shades of gold, blue, purple, or red.
While they are certainly pretty to look at, these Palearctic natives can be pests. They are notorious for their ability to reduce entire fields (especially rhubarb) to nothing but plant skeletons!
On the other hand, though, this same ability makes them the perfect candidates for biocontrol to benefit other types of crops. Farmers are currently exploring using these insects to weed out tough, stringy dock in hay meadows.
5. Green Rose Chafer (Cetonia aurata)
The green rose chafer is another larger green iridescent beetle species, measuring around 17-20mm. It has been described as “somewhat like a bumblebee,” not only in size but also in that it flies noisily and clumsily.
Apart from being easy to spot due to its size and bumbling nature, it also bears the distinct feature of a prominent v-shaped sculletum or plate between elytra. Its underside is also uniquely copper in color.
The green rose chafer has interesting historical roots. In ancient Egypt, it was held sacred as a symbol of immortality. It was later believed to be an antidote to rabies in 19th-century Russia. Today, it plays an important ecological role in both flower pollination and helping decompose organic waste.
6. Six-Spotted Tiger Beetle (Cicindela sexguttata)
The six-spotted tiger beetle is perhaps one of the easiest green iridescent beetles to identify, with its long legs, large overlapping mandibles, and white spots on the elytra. However, it is also worth noting that its signature white spots do not always come in six sets, as its name suggests. Individual beetles can have more, less, or even none.
As the “tiger” in its common name suggests, the six-spotted tiger beetle is a skilled hunter. Even as larvae, they prey on insects such as spiders, just waiting to grab them with their mandibles and drag them down into their burrows. They are equally voracious predators in adulthood, using their keen vision, stealthy camouflage, and quick movement to their advantage.
7. Delta Ground Beetle (Elaphrus viridis)
Last on the list but not the least is the elusive delta ground beetle. This bright (almost lime) green iridescent beetle can only be found in the small region of Jepson Prairie in Solano Country, California. Currently, its entire range is constricted only to those 2,800 hectares of prairie, where it lives on the edges of vernal pools.
Its population is relatively small and geographically constricted, so it has not been as extensively studied as other beetles. According to scientists, there is still much to be learned about its lifecycle and behavior. Still, one easy way to identify these insects is by their triangular pronotum, from which it likely got the “delta” in its name.
Sadly, the delta ground beetle was officially listed as a threatened species in the 1980s. Agricultural practices, urban development, and climate change all contribute to the destruction of its vernal pool habitats and as a result, its population. Fortunately, conservation efforts have been launched, and continue to this day.
Green Iridescent Beetles, Conclusion
Again, this list is by no means a complete guide to green iridescent beetles, let alone the order of Coleoptera as a whole. Hopefully, though, this article inspires you to keep an eye out for them the next time you are out and about in the garden or taking a stroll.