BEETLES A N D M A N
S. Louw
Every fifth kind of liv in g th in g is a beetle.
(P h oto : c H E Jaques, 1951).
It is estim ated that 350 00 0 different species of beetles (Coleoptera) are know n to science today. This makes the Coleoptera the largest group of living organism s by far and in fact means that one out of every five kinds of living thing s in the w o rld is a beetle. M any people associate beetles w ith the field, flow ers, trees and the countryside in general. W hile th is is true fo r most beetles, many species affect man by invading his home, crops, barns and food stores.
U sually beetles, like other anim als and plants, are kept in a state of balance by natural factors such as food, climate, disease, parasites and predators. U nfortunately man disturbs this balance by either providing conditions for a species to m u ltip ly or by introducing alien species w ith o u t their fu ll range of natural enemies. On account of th is a state of affairs is brought about that is prejudicial to m an's own activities and he has to control the situation. This m ostly results in so-called 'chem ical w a rfare' where man resorts to insecticides in order to eradicate the pests he him self is responsible for. U nfortunately these insecticides are m ostly used overzealously w h ich fu rth e r disrupt the balance of nature, thus creating a 's n o w b a ll" effect . . . Stored products have, ever since Stone Age man, probably been the most ideal m an-established living space for many insect pests. Currently some 150 species, the m ajority of w h ich are beetles, infect m an's food supplies. A n n u a lly one quarter of the w o rld 's food supply is destroyed, resulting in a finan cial loss of approxim ately U.S. $ 25 ,0 0 0 m illion. Probably the most im portant beetles in this regard are the cosm opolitan grain weevils (S ito p h ilu s spp.). w h ich attack all form s of grain — the staple diet of the w o rld 's population, and the cowpea bruchid w hich destroys vast quantities of cowpeas (e.g. in Nigeria 250 0 0 0 tons of th is product are lost annually on account of th is beetle). Closer to home, good examples are the Bean gall weevil
Alcidodes erythropterus w h ich attacks the seeds
of various legumes, w h ils t the Potato snout
The G rain w eevil, a com m on pest o f stored w hole grain.
(P h oto : c The M arilyn P u blishing Group Limited. 1979)
The Bean gall weevil.
(P h o to : c B utterw orths & Co (SA} (Ply) Ltd. 1982)
T h e P o ta to s n o u t b e e tle .
(P h o to : c B u tte rw o rth s A Co (SA) (Pty) Ltd. 1982)
T h e W h it e - f r in g e d b e e tle .
{P h oto : c B utterw orths & Co (SA) (Pty) Ltd. 1982).
beetle Sciobius h o rn i damages potatoes in the eastern Orange Free State.
Examples of the pests w h ich have been in tro d u c e d are the W h ite -frin g e d beetle
G raphognathus leucoloma w h ich extensively
damages pastures and crops, the Eucalyptus snout beetle G onipterus scutellatus w h ich attacks eucalyptus trees and the Pine weevil
Pissodes sp. w h ich injures pine trees.
Pests have also become domesticated and are now so closely linked to man that they are d iffic u lt to find in their natural habitat. For example the Varied carpet beetle A n th re n u s sp. extensively damages clothing, carpets and museum collections, the Death w atch beetle
Xestobium sp. attacks tim ber structures and the
Common fu rn itu re beetle A n o b iu m pu n cta tu s ruins fu rn itu re and timber. A. p un ctatus is also
T h e P in e w e e v il.
(P h oio : c B u tterw orths & Co (SA) (Pty! Ltd. 198 2)
The E u c a ly p tu s s n o u t b e e tle .
(P h o to : c B u tterw orths & Co (SA) (Pty) Ltd. 1982).
A Dung beetle ro llin g a ball of dung.
(P h oio . c B utterw orths Pub. (Pty) Ltd. 198 5)
an example of an alien species w h ich has accidentally been introduced into South Africa. M an's association w ith beetles has, however, also a brighter side and many beetles are in fact very useful. Possibly one of the greatest benefits to man is the role they play in pollinating flowers. For example the Oil palm weevil Elaeidobius
kam erunicus is used to pollinate Oil palms in
Malaysia and are estimated to have an annual pollination value of approxim ately U.S. $ 115 m illion.
Beetles also help to keep our environm ent clean by acting as scavengers. Byeating dead animals, decaying plants and dung they can rig h tfu lly be dubbed the dustmen and nightcartdrivers of the
An adult Ladybird beetle sinks its ja w s into an aphid.
(P hoto, c A n th o n y B a n n is te r. 1 97 9)
countryside!
Beetles are also of great importance in biological control (i.e. where one organism (the pest) is controlled by other organism s (the natural enemies),. A w e ll-kno w n example is the control of scale insects and plant lice by the Ladybird beetle (Coccinellidae). In South A frica much progress has been made in controlling noxious plants by means of introducing their natural beetle enemies. The notorious Silky hakea, Hakea
sericea for instance, seems to be affected by the
attack of certain erirh in in e weevils, w h ile the Long-leaved w a ttle , A ca cia lo n g ifo lia and Stinkbean A lbizia lophanta are attacked by cryptorynchine weevils and the Lantana Lantana
camara is defoliated by cassidine leaf beetles.
GEOLOGICAL RESEARCH AT
FLORISBAD
The occurrence of fossils in the spring deposits at
Florisbad, approxim ately 42 km north of
Bloemfontein, has been know n since 1912 when the area was developed as a spa. However, particular attention was focussed on the Florisbad site when a fossilised (now w orld famous) hum an skull w as unearthed in 1932. During 1980 the National Museum acquired Florisbad as a research station and since has u n d e r t a k e n e x t e n s iv e a r c h a e o lo g ic a l excavations in order to find more fossils and to
B .S . R ubidge & J .S . Brink
study the sedimentary deposits.
One of the objectives at Florisbad is to determine the structure and nature of the soil below the surface and for this purpose thirty-one boreholes were drilled at various points under the supervision of Dr Clarke during 1981 and 1 982. Samples of the sediments were taken at various intervals in each borehole, and their precise depth of origin noted.
