Bug has a long, colourful history

I’M BEHIND schedule with my gardening this year. Mind you, nature is a bit behind schedule too. Blackthorn blossom and primroses in May — they should be flourishing in March. The soil in the vegetable plots is cold.

I was doing a bit of digging the other day, trying to catch up, and I came across something rather odd. It was a pale coloured grub, a bit like a caterpillar, and it was huge — about the size of my little finger.

I thought I knew what it was, but I checked a book to be sure. I was right, for once. It was a ‘white grub’ or ‘chafer grub’ — the larva of a cockchafer.

Cockchafers are beetles of the scarab family. Adults are on the wing in May and early June. They’re clumsy fliers with a habit of bumping into things, and sometimes people, and they’re big — the size of two thumb nails. The ridged wing cases are brown and the head and first joint of the body are black. The body is hairy and they have strange boat-shaped antennae that are larger in the male insects.

They also have a rather unusual life cycle. About a fortnight after they first appear, the mated females start to lay eggs. To do this they land on the ground and burrow down for between 10 and 20 centimetres. They usually choose grassland — a pasture or a lawn — though one of them obviously picked my vegetable garden. Females may do this several times until they have laid between 60 and 80 eggs. Then they die. Mature winged beetles only survive for five or six weeks.

About a month later the eggs hatch into larvae or grubs. They live underground for four or five years, feeding on the roots of plants and getting steadily larger. At this stage they can be a bit of a nuisance because the roots they eat include things like potatoes and carrots.

Early in the autumn, mature larvae pupate and, about six weeks later, turn into beetles. The beetles stay underground; sometimes in cold weather they will burrow as deep as a metre below the surface. Then, the following May when the soil warms up, they make their way to the surface and fly off to look for a mate. Another name for them is May Bug.

Cockchafer populations run in cycles. The winged insects are particularly abundant about once every four years. There also appears to be a larger cycle of 30 or 40 years superimposed on this in which they appear in unusually large numbers.

At least, this used to be the case. In the 1970s cockchafer populations crashed all over Europe and they became extinct in many places. The reason was probably the introduction of new pesticides. Most of those pesticides are now banned in Europe and there has been a slow increase in numbers in recent years.

HISTORICALLY they reached plague proportions, with 1911 a “cockchafer year”, and there is a record from the continent of 20 million insects being collected and destroyed in an area of only 18 square kilometres.

In 1320 they gave rise to one of the most ludicrous events in the history of the relationship between human beings and wildlife. Cockchafers were summoned to a court in Avignon and sentenced to withdraw within three days to a specially designated area on pain of being outlawed. When they didn’t obey they were collected and killed. The same court passed a similar sentence on mice.

There was also a time when people ate cockchafers. I have a 19th French recipe for cockchafer soup.

I haven’t tried it. It needs 500 grams of cockchafers with the wings and legs removed, and they are rather rare nowadays.

* dick.warner@examiner.ie


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