Carabidae (ground beetles)

Carabidae overview - Cychrus caraboides - Brachinus crepitans (Bombardier beetle) - Loricera pilicornis - Harpalus rufipes (Strawberry seed beetle) - Carabus nemoralis - Harpalus latus - Pterostichus niger - Pterostichus madidus

Carabidae (ground beetle) Family

There are over 30 000 species of Carabids (ground beetles) in 1500 genera world wide, 725 specie in Europe and over 350 in the UK. They are usually found on the ground and can run fast. The adults range in length from 3 - 36 mm, and are mainly nocturnal. Many of the European carabids are voracious pradators of snails, slugs and many other invertebrates, so should be cherished by gardeners.

In areas where the weather is cold, many species hibernate during the winter. The drawing and photograph below shows a typical carabid larva. The abdomen has 10 segments including the anal tube, 3 leg-bearing segments making up the thorax, and 1 head segment.

Cychrus caraboides Many ground beetles are specialists, e.g. Cychrus caraboides (see left and below) feeds solely on snails and has a narrow head and thorax to enable it to better reach its prey. Adults can be seen all the year round, and are 16 - 21 mm long. Cychrus caraboides is also able to squirt yellow acid out of its rear end with some accuracy in order to startle any predator. I can vouch for the accuracy having received a full load in the face when I was restraining one for a mark and recapture exercise by

attaching it to a broom handle with an elastic band. Not all science is high-tech!

And if that were not enough it can also stridulate when picked up making a noise some describe as a squeak, but I think is more of a metallic hiss. When resting it is found under stones and logs.

The larva can grow up to 20 mm long, and unlike other carabid larva, it is short and fat. Like the adult is live mainly on slugs and snails, and can be seen in the autumn.

Cychrus caraboides should not be confused with the bombardier beetle (Brachinus crepitans) whose anal discharge is truly explosive and goes off with a pop and a puff of smoke. The adult has a red/tan thorax and legs, and blue/black wing cases.

The explosion is caused when two substances which are safe when

stored separately in abdominal chambers are mixed in contact with the air. The temperature of the explosion is around 100 ^oC, and can be aimed with considerable accuracy. About 12 explosions can take place in fairly rapid succession before the reservoir of chemicals is temporarily exhausted.

Adults are seen in August in chalky districts in the south of England, Wales and S. E. Ireland. By day they tend to hide under stones, and their favourite habitat is river and stream banks.

Loricera pilicornis

Loricera pilicornis is on the left and right. It is from 6 - 8 mm long, and tends to inhabit wet or damp places.. It is very easy to recognise this beetle by the long bristles on the first 6 segments of its antennae. It uses these bristles to form a sort of cage in front of its mouth to trap springtails and mites, which are its favourite prey.

It has 10 regular striations on each elytron, and in the fourth interval there are 3 round depressions.

Harpalus rufipes

Harpalus rufipes is another specialist, it eats the tiny seeds on strawberries, this does not damage the fruit, but does spoil its appearance. This beetle is also known as the strawberry seed beetle.

The adult is 14 - 16 mm long, has a black body with reddish-brown legs, antennae and mouthparts.

Carabus nemoralis

Left, right and above are photographs of Carabus nemoralis, a stunningly beautiful beetle - a male above left and female in the centre. It ranges in size from 18 - 28 mm, the elytra have a copper sheen with irregular ridges and three lines of pores down each elytron (see the photograph above right). It is found throughout Europe and in most habitats. It has been introduced to North America.

On the left is a close-up of the fearsome mandibles used for crushing and slicing through prey - it will eat or try to eat any animal it can.

Above right is a close-up photograph of the tarsal pads of the male in the photograph above left. These are on the underside of the first pair of legs. Tarsal pads are found in many Carabid beetles, especially those which climb. However in other species they are restricted to the males. They are thought to help the male cling to the female during mating - which can be prolonged. The pads are spongy and made of rows of spoon-shaped bristles. All Carabidae have 5 segments to their tarsus.

Carabus nemoralis adults are seen mainly in August and September, and are active at night.

Harpalus latus

Harpalus latus on the left, adults range from 7 - 11 mm long. It is a fairly common beetle found in many habitats, but most often seen in the summer in woodland or shaded ground under moss, fallen branches and leaf litter.

Pterostichus niger

Pterostichus niger on the right. This is a preserved specimen of a female adult. The adult body length ranges from 15 - 21 mm, it is often found under bark or rotting wood on all kinds of soils except the very dry, and hunts mainly at night. It is common throughout the U. K. and Europe, and is also found in North America. Note that it is entirely black except for the last few segments of the antennae.

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