Friday, 29 June 2007

Soldiers and sailors line the lanes

Throughout the months of late spring and summer, the lanes of Norfolk are dressed with the soft white tones of umbellifers. These erect and architecturally interesting plants are members of the carrot family, with their narrow branching stems topped with groups of small white flowers. A succession of species flower as the months progress, starting with the cow parsley that is at its best during May. From late May through into July it is replaced by the somewhat less showy rough chervil, which in turn is replaced by upright hedge parsley come August. These are interesting and diverse plants, which occupy a range of habitats and include species that are edible (for example, alexanders), while others (such as hemlock) are deadly poisonous; hemlock is perhaps best known as the poison given to Socrates at his execution.

As a non-botanist, my interest in these plants is in the diversity of invertebrate life that they attract. Visit a patch of umbellifers on a fine day and you are almost certainly going to encounter some rather smart beetles, various small hoverflies and possibly even a scorpion fly or two. Some of the beetles most often encountered belong to a family called the Cantharidae, better known as soldier beetles. They are typically a couple of centimetres in length, with narrow parallel-sided bodies and brightly coloured wing cases (known as elytra), and they will be familiar to those who have spent anytime in the countryside during summer. There are 40 species of soldier beetle in Britain; many have red or yellow wing cases but others are dull blue or even black. Some authors refer to the dark coloured species as sailor beetles, reserving the name of soldier beetle for the red or yellow coloured species. While this may reflect an association with the traditional uniforms of the different branches of our armed forces, the distinction is pretty unhelpful in the field, especially when it comes to attempting an identification. This is because the colours shown by individual species of soldier or sailor beetle can be very variable; while one individual may be red, another of the same species may be a dirty brown or almost black.

The adult beetles and their larvae are fluid feeders and, while they may feed from plant material, they are typically carnivorous in their habitats, feeding on dead or injured insects. They will also tackle healthy live prey if it is small enough or slow enough to overcome without the risk of injury. These beetles, therefore, are not simply visiting the umbellifer flowers for nectar or pollen. Instead, they are here to find more substantial rewards, in the shape of other insects for food, or a mate to continue their lineage.

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