VALUE OP FROGS.

Press, Volume LXXII, Issue 21743, 27 March 1936, Page 21

VALUE OP FROGS.

RESULTS OF YEAR’S?

, RESEARCH

DESTRUCTION OP INSECTS

(fatm oca owa ooaMßfosD*KT.)

LONDON, February if. Frogs gritted a new importance at a: meeting of the Zoological Society in London yesterday. Mr Ivan Sanderson, on the strength of a year's collecting in the little known forests of the British Catneroons, presented the society with striking evidence that changes In the frog population :of tropical countries, brought about by the clearing, of forest land, may have important results on the encouragement .of plant pests ahd tile, spread of disease, , i /.This is believed to be the first time that the importance frogs to man'kind has been conclusively demonstrated. ' The key to, the situation, according to Mr Sanderson, is the enormous number of insects eaten by frogs, and the •astonishing extent to which the frog population is reduced by clearing operations of almost any kind. . . During the travels of the expedition, about 1000 frogs, of 40 different kinds wm*e collected, Mr Sanderson found ,thst 60' per cent. of these species were confined, not merely to a particular 'zone, of vegetation, but to special conditions within that zone. . also this is regarded as the economically significant part of his- investigation—mat marked changes in the number of frog species are producedhy* ,ehangesvin the state of the land, The frog population, and thereforb:its insect.eating proved to fie roughly proportional to the number of kinds- of- frogs present. * A total of'2B. different species eLfrog in deelduoUs forest givfi place to-only 18 species -when the forest is cleared, while when mountain forest is cleared, giving 'placfc to grass, the: invariable formmn'er of desert,, the numfierof Speclfes is reduced to three, • r ’ v Among rAhe diseases ; by Mr .Sanderson' were 'malaria, yellow fever, *)jie#inr Sickness and sandfly fever. Among the crops In which insect; infestation presents various problems are tea, cocoa, coffee, cotton and tobacco, in all such cases he believes that measures for the encouragement of the frog population are worthy of trial.