Finding beetles at Trekenner!


Between us, we could probably cover several pages of information after listening to Ian MacClenaghan talking about beetles on Sunday morning when a group of twelve, then thirteen, then fifteen and finally sixteen and two children joined Ian to find out about beetles and the methods he uses to catch and record them.

I will start with snippets from his introductory talk and I'm sure others will have more to say from his commentaries along the way.

Beetles need warmth to give them energy (which is probably why so many were active the day before at Stara Woods in the dappled sunlight along the paths~ we were not so lucky on Sunday which remained dry but with a rather over-keen wind from the north west). Many beetles are dark in colour and absorb the sun's rays and we discussed the structures that refract light to give the effect of iridescence.

Dock Beetles

As for some number crunching, there are about three quarters of a million species world-wide; 4,100 in the British Isles of which 1,400 reside in Cornwall which is actually too wet for many beetle species to thrive. The damp encourages bacteria and fungi which can infect and kill beetles at all life stages. This may account for the apparent gaps in distribution across Britain.

The antennae are their main sensory organ with 11 segments or joints; separate and simple in the more primitive species but increasingly complex in others with segments evolving to perform different functions. Ian described the actions of various hairs or bristles which can be relatively hard along the sides of the beetle acting rather like cat's whiskers to give an indication of the space on either side or, on the upper surface of the head and thorax/pronutum, they can be very delicate, sensing the slightest change in air movement to give warning of a predator. 

We learned about life stages: that the larger beetles can live for up to four years; the details of the life sequence of oil beetles; that dung beetles can bury down to a depth of about a metre; Dor beetles regurgitate food to feed their young. Some basic identification can be made by the shape of the tunnel a beetle makes which is dependent on the mobility of  the head & pronutum; tropical species from the West Indies can cross the Atlantic in driftwood and then emerge on the beach and make their way inland to breed on species like Holly (for example).  

Beetle collecting 1

Ian has made great use of a motorised garden leaf blower set in reverse to suck up invertebrates from the ground or from bushes. This is invaluable to him because of his interest in the smaller beetle species, many of which are only 1-2 mm long.

For the rest of the morning we checked pitfall traps set two days previously; studied the output from Ian's leaf collector; beat various shrubs in the hedges using white sheets/beating trays to collect the fallen; Hawthorn proving to be the most productive possibly because of the pollen beetles feeding on the blossom. Ground and Rove beetles were collected from under stones.

Around the ground sheet

After all this we were more than ready for lunch (we forgot elevenses!) and we all enjoyed an al fresco lunch with much to share and some lovely cake ~ thank you to all who contributed.

We await a list of species from Ian; I have noted a few other non-beetle species of interest but really, we must thank Ian very much indeed for giving us his time and expertise and of course, the other Ian and Irene for lending their field for the occasion.

A larger ground beetle Maybe some more photos soon?  

A beetle hunter at work!


Calendar Event associated:
Species Seen:
Flat-backed Millipede, Common Ground beetle, Centipede, Dock beetle, Chiffchaff, Swift, Swallow, House Martin, Greater Spotted Woodpecker, Common Toad, Mole (dead), Rabbit and Deer signs. There will be more than this!