Hemiptera: True Bugs

Most people tend to call anything with lots of legs a "bug." However, to an entomologist, a "bug" is one of the 82,000 or so species of the order Hemiptera.

The Hemiptera (Bugs) are a diverse Order of insects, which display a mesmerising array of body forms.  There are nearly 1800 British species, almost all feeding on the sap of a wide range of vegetation. They include many groups that we frequently encounter, such as leaf hoppers, shield bugs and aphids.  There are also aquatic species, including the well-known Water Boatman.  Many (such as aphids) are crop pests, and are thus economically important.  A few are active predators, whilst others are blood-suckers (Bed Bugs).

Identifying Bugs

The Hemiptera can be distinguished from other groups by the fact that they have ‘sucking mouthparts' specially for feeding on liquid substrates such as plant sap and blood.  There is a close analogy to human beings employing drinking straws for beverages! However, as with all identification features, these are not ubiquitous, and are sometimes reduced or missing altogether. (e.g. in male scale insects).

Just to confuse us even more, the Order is separated (rather controversially) into two sub-Orders; the Homoptera and the Heteroptera.

•  Homoptera: Fore wings uniform throughout, being either entirely membranous (e.g. aphids), or entirely hardened (e.g. the hoppers). When at rest, Homoptera fold the wings roof-wise over the body.


 •  Heteroptera: Only the tips of the fore wings are membranous, the basal part being hardened or leathery (e.g. shield bugs).  In some groups, wings may be missing or reduced to short wing-pads. When at rest, the Heteroptera fold their wings flat and slightly overlapping.

In particular, the mealy bugs and scale insects may cause some confusion.  The females, sometimes legless as well as wingless, may appear grub-like, whilst males have one pair of wings and no sucking mouthparts!

Insects such as butterflies, flies and beetles, undergo what is known as ‘complete metamorphosis' (or holometaboly).  In other words, the immature, larval stage is completely different from the adult.  Think of a butterfly: the caterpillar, and chrysalis look nothing like the adult butterfly.  Maggots look nothing like adult flies, and grubs, or ‘leatherjackets' do not resemble adult beetles.  Bugs on the other hand, undergo in-complete metamorphosis (or hemimetaboly).  Instead of larvae, immature bugs are known as nymphs, and undergo a series of successive changes, which make them look more and more like adults with each moult.

The easiest way to tell the difference between an immature bug (nymph) and an adult, is that only adults possess wings.  However, as afore mentioned, a few species do not possess wings as adults.  All this really does add to the confusion, but as a rule, it is a good one to stick by.

Identifying Bugs to the family level is achievable by the amateur using a good text, such as the AIDGAP key produced by the Field Studies Council: Unwin, A key to families of British Bugs (Insecta, Hemiptera).  The guide is limited to what can be achieved by examining unprepared specimens at low magnification (up to x50), as the scale insects (Coccoidea) and aphids (Aphidoidea) require more sophisticated techniques that are beyond the scope of this guide. However, lists of the characteristics of the main aphid families are given.

Interesting Bug facts!

The Hempiteran family known as the Pentatomidae are commonly known as the 'Stink Bugs'. Pick one up, and it may secrete an unpleasant-smelling substance which might also leave orange or yellow stains on fingers. These secretions come from a pair of glands on the thorax.

A number Hemiptera, particularly the Acanthosomatidae, are renowned for parental care-at least one of the adults will remain with the nymphs, sometimes all they way through the life cycle.

A few species of scale insects (Coccoidea) are of great value in the production of useful commodities, such as shellac, cochineal and various waxes, although nowadays some of these products have been largely replaced by synthetic materials.