The term ‘bug’ is largely used in an informal context to describe a large range of species, including butterflies. However, technically the only bugs are true bugs, such as shieldbugs, and butterflies are not a part of this group.
What is a bug?
Who didn’t love a bug hunt as a child? Lifting up rocks, staring into spiderwebs, even picking up a wiggly worm. Whether they hop, slither or skitter, we are all happy to label each and every one of these little creatures a bug.
Fear them or love them, bugs are everywhere. Yet, look to any entomologist and point out these many little creepy crawlies and it’s unlikely they will be satisfied with the word ‘bug’. In entomological terms, the only bugs within all this bustle are the true bugs.
True bugs are a type of insect within the Hemiptera order. The group is amazingly diverse and large, compromising over 80,000 different species.
What sets them apart from other insects is their stylets, a tubular arrangement of the various mouthparts to form a kind of sucking tube. In the majority of species, this adaptation is used to suck out sap from plants, however, a few have adapted it to feasting on blood instead.
Some well-known members of the group include cicadas and aphids. These animals are well known for piercing the skin of plants within their stylets and feeding on the sap below, the excess being expelled through the production of honeydew.
Shieldbugs are another commonly seen incarnation of the true bug group, yet while the majority of them are friendly neighbourhood herbivores some have turned carnivores, hunting down smaller insects.
Even less popular are the bedbugs, which have turned their needle-like mouthparts to piercing skin and sucking blood.
Is a butterfly a true bug?
It might be easy to confuse a butterfly for a member of the true bug family. The stylet is in many ways very similar to the butterfly’s proboscis, a long thin tube that is used to suck up the nectar from flowers.
However, one of the main differences is that the proboscis is much more flexible and able to curl up under the head of the butterfly when not in use. It is also much longer. Many of the characteristics true bugs and butterflies share are to do with them both being insect groups, such as the hard exoskeleton.
The butterfly belongs to a separate order of Lepidoptera, which also includes moths. This order does not sit within the true bugs.
What is an insect?
Both Lepidoptera and Hemiptera are insect groups. Many people use the word ‘bug’ and the word ‘insect’ interchangeably. However, while ‘bug’ is used as an informal term the word insect is much more precise in its meaning.
For example, ‘bug’ may be used for worms, spiders and millipedes, yet none of these are insects. They all belong within the Arthropod phylum, which is a diverse group with segmented bodies, exoskeletons and pair appendages.
After this, the insects become separated from others in the groups such as molluscs, which include worms, Arachnids, which includes spiders and the Myriapoda, which includes millipedes.
Insects, as a group are defined as having three pairs of jointed legs, a pair of antenna, an exoskeleton, and three sections to their bodies; the head, thorax and abdomen. Within the insect group are included flies, beetles, grasshoppers, and many other species, such as the butterflies.
Is a butterfly a bug?
A butterfly is an insect but not a member of the true bug family. However, in terms of what we might call them when out with a butterfly net on a family bug hunt, they would most certainly be called a bug.
While entomologists may not enjoy the lack of accuracy in the term, there is something friendly and familiar about the word ‘bug’. It stems from a time when we were less interested in how to divide up the world and more certain that things that are small, and spend their days crawling or flitting through the world around us, are bugs, without further need for explanation.