Hawthorn Shield Bug by Mark Butler

The word “bug” can have many different meanings, it can be slang for when someone is irritating you (“don’t bug me”) or a device that spies use to listen in on conversations. Most often “bug” is used to refer collectively to insects and other invertebrates, but to a taxonomist (a biologist that groups organisms into categories) this usage would be considered incorrect. Bugs, or “true bugs” because of aforementioned misuse, are insects within the Hemiptera Order. This means that all bugs are insects, but not all insect are bugs.

In the world there are over 70 000 true bug species, 1 800 of which are found in Britain. This order includes shield bugs, plant hoppers, bed bugs and aphids.

So what sets the true bugs apart from other insects? The main difference boils down to mouthparts.

True bugs pierce plants with a long, rigid and straw-like proboscis (mouthpart). The proboscis of the true bug is non-retractable, meaning they cannot chew. Instead, once they have pierced the plant, they push their saliva through their proboscis into the plant, which begins digesting the plant material, after which they suck up the food (plant sap) through their proboscis. Most other insects with a similar proboscis, for example butterflies and bees, are able to retract their proboscis.  This allows them to move food into their mouth, whereas the true bugs can only pierce and suck the plant.

Another characteristic trait of some true bugs, though not all, is that half of their forewings are hard and leathery, while the other part is soft. This is reflected in their taxonomic name “Hemiptera”, hemi means ‘half’ in Greek and pteron means ‘wing’.

Some of these plant-piercing species are considered pests, in Britain there are 800 species of aphids, whiteflies and scale insects. As well as damaging and weakening crops by feeding on the plant they can transmit disease from plant to plant too.

So the next time you are pestered by aphids in your vegetable patch, be sure in the knowledge that you are being bugged by a true bug.

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