June, 1909.] 



517 



Plant Sanitation! 



mental plots of manurial plants now 

 growing on the Peradeniya Experiment 

 Station afford a good object lesson of 

 the relative immunity from insect pests 

 of the several species of Crotalaria. 

 The difference between two adjacent 

 plots of C. verrucosa and C incarna 

 respectively, is most noticeable. The 

 former is virulently attacked by a 

 minute ' Flea-beetle ' (? Haltica sp.) which 

 riddles the foliage with minute per- 

 forations to such an extent that the 

 growth of the plants is completely 

 checked. The same species has, at the 

 same time, been extensively defoliated 

 by the caterpillars of a moth {Deiopia 

 pulchella, Linn.). The incarna plot 

 is practically free from either of these 

 insects and shows a most luxuriant 

 growth. The seed pods of all the 

 species of Crotalaria are attacked by 

 the caterpillars of two small blue butter- 

 flies (Polyommatus boeticus, Linn, and 

 Jamides bochus, (Jram.). Though the 

 presence of these pod borers diminishes 

 the seed supply, it does not affect the 

 manurial value of the plants, especially 

 as the best results are probably obtain- 

 able by digging in the plants before they 

 have ripened their seed. 



The ' Tobacco stem-borer ' (Gnorimos- 

 chena heliopa, Lower) has necessitated 

 the premature destruction of the tobacco 

 plots on the Experiment Station. This 



Eest is well known in Java, where it 

 as been found that nothing short of 

 eradication of the affected plants is 

 possible. 



The ' Pear Aphis ' (Lachnus pyri, 

 Buckton) has been sent in from Kanda- 



Sola- This species was first noticed in 

 uwara Eliya, more than ten years ago, 

 but has not attracted attention for some 

 time. It appears, in dense clusters, on 

 the stems and branches of pear trees- It 

 is readily exterminated by an applica- 

 tion of kerosene emulsion. The species 

 is known only from Ceylon. 



Injury to growing rice by the ' Paddy 

 Bug ' (Leptocorisa acuta, Thunb.) is re- 

 ported to be very severe in the Triu- 

 comalie district. Ears of rice sent in to 

 this office were found to be completely 

 empty. Not a single grain had been 

 allowed to mature. Circular No. XL, of 

 the Ceylon Agricultural Society (com- 

 piled by Mr. C. Drieberg) embodies most 

 of the known means of combating this 

 pest. As a preventive measure, the 

 grass growing on the bunds and in the 

 fallow paddy-fields should be periodi- 

 cally burnt off. The Paddy bug breeds 

 on the inflorescence of these grasses, 

 when there is no paddy for it to feed 

 upon. A periodical burn will destroy 

 enormous numbers of the insects and so 

 greatly lessen the danger of serious 

 injury to the rice fields. 



NOTES ON THE VALUE OF INTRO- 

 DUCED PARASITES OR BENE- 

 FICIAL INSECTS. 



By Walter W. Frogatt, f.l.s., 

 Government Entomologist, New South 

 Wales. 



(From the West Indian Bulletin, Vol, 

 IX,, No. 3, 1908.) 



At a Conference of Government Ento- 

 mologists held in Sydney, J uly 8 to 10, 

 1900, convened by the Minister of Agri- 

 culture to consider the interstate laws 

 dealing with the export and import of 

 fruit and plants, and the control of 

 insect pests, a resolution was carried 

 by the members on " The expediency of 

 personal inquiry as regards parasites in 

 California," and it was suggested that I 

 should be sent to report upon the work 

 done in Hawaii and California. 



Nothing further came of this sugges- 

 tion, though in the meantime our 

 Minister got a Bill through the House 

 giving power to compel orchardists to 

 clean up their orchards and destroy, by 

 burning or boiling, all infected fruit. 

 This is known as the ' Fruit Fly and 

 Codling Moth Act.' Last June at a 

 Conference of the State Premiers held in 

 Brisbane, the Hon. C. Swineburne, of 

 Victoria, proposed that the Government 

 Entomologist of New South Wales 

 should be sent round the world to see 

 what methods could be discovered to 

 deal with fVuit flies, either by parasites 

 or mechanical methods, to study other 

 cosmopolitan pests, and to report upon 

 the value of parasites generally. 



The question of parasites had become 

 very acute in Australia through the 

 action of California and Western Aus- 

 tralia. It was claimed that there were 

 no injurious scale insects in Hawaii, 

 California, or Western Australia, that 

 the lantana scrub had been killed out by 

 inttoduced phytophagus insects, and 

 that the codling moth parasite from 

 Spain was spreading all over California 

 and doing such good work that spraying 

 and fumigation were things of the past. 

 I was requested to visit a large number 

 of countries to report upon parasites 

 and their value, particularly in Hawaii 

 and California, and 1 have spent a con- 

 siderable amount of time in the field and 

 orchards in studying the question. 



I found in Hawaii that scale insects 

 and mealy bugs were just as plentiful 

 upon native bushes and introduced 

 plants as they are in Australia, but as 

 there are practically no commercial 

 orchards in these islands, very little 



