218 



THE AGRICQLTDRAL NEWS. 



July 8, 1911. 



INSECT NOTES. 



THE ROOT BORER OP THE 

 SUGaR-OANE. 



The root borer of the sugar-cane (Diajirepes abbre>'iatus), 

 •which appeared as a serious pest in a limited area in Barba- 

 dos at the end of 1909 and early in 1910, was again in 

 evidence and caused serious injury to ripening sugar-cane 

 during the first months of the present year. 



General accounts of these occurrences of the root borer 

 have appeared in the Agricultural Xews (see Vol IX, pp. 10, 

 58, 106 and 410). In the West Indian Bulletin (Vol. IV, 

 p. 37), a paper \va.s published, by the Rev N. B. Watson, 

 r.E.S., on the root borer of the sugarcane, in which the life- 

 history of this interesting pest was given in detail. Mr. Watson 

 observed that the root borer adult weevil (Fig. 10) was to be 

 found during Augu.st and September, and it was at this time 

 that the eggs were laid which provided for the next generation 

 of grubs (Fig. 9). This year, the weevils have appeared 

 earlier than the __»wm,».,^j time given in pre- 



female probably often exceeds 250; these are laid in several 

 clusters at different times. 



The ei.'gs are about four times as long as broad, the 

 length being about ^-mm. The grub.s, on hatching from 

 the egg, at once drop to the ground, and it is likely that 

 ants capture and devour a verj- hni^e percentage of them 

 before they can penetrate into the soil. When it is first hatched, 

 the grub is considerably larger than the egg from which it 

 has emerged. Its colour is white, except for the head, which 

 is pale-brown. 



Every effort should lie made to discover the eggs, and to 

 collect these as well as the weevils. It is during these two 

 stages of the root borer's existence that it exposes itself to 

 easy and successful control by man. The long period of 

 nearly a year, when the grub and pupa are underground, is 

 the time when the pest is so protected by its mode of life 

 as to be very safe from attaclv. 



vious records: per- 

 the unusual rains 

 the early months. 

 20, Mr. A. A. 

 of Spencers plan- 

 finding these in- 

 and he has adopt 

 Fig. 



haps on account of 

 which fell during 

 Since about June 

 Evelyn. ^Manager 

 tation, has been 

 sects in abundance, 

 ed the plan of 

 9. Grub of Root Borer. 



collecting and destroying them. They are found hiding in 

 the throat of yourg corn and under the base of the leaf 

 of older corn. They also conceal themselves among the 

 leaves of other plants, and it is during this period of hiding 

 that mating of the sexes takes place. Eggs have not been 

 found in the field, but in the entomo- 

 logical laboratory of the Imperial 

 Department of Agriculture these were 

 obtained on June 27, and they were 

 observed to hatch on June 30. These 

 eggs were obtained from weevils, brought 

 in on June 23, and were laid between 

 the 24th and 27th. The time spent in 

 the egg in this instance was not more 

 than six days. 



Planters in any district where the 

 root borer is known to occur would do 

 well to keep a careful look out for 

 these insects, and to have them collected 

 when they appear. The weevils are 

 easily found and readily captured; but 

 once the eggs are hatched, proper control 

 becomes next to impossible. 



A crop of Indian corn might well 

 be planted where badlj' attacked canes 



have been reaped, and this would .serve ^i''- H- t.R.viN Weev 

 as a trap where the adults could be captured. The period of 

 pupation is passed in the ground, and when this is completed 

 and the weevils emerge, the corn [ilants furni.sh a suitable 

 hiding place for them. If no such convenient hiding place 

 is found, the weevils probably flj' away in search of some 

 suitable location, and thus become so scattered as to render 

 collection impossible. 



In the laborator}', the eggs have been laid on leaves of 

 Indian corn, imphee and sweet potatoes. They are generally 

 covered by a fohl of the leaf, or by two leaves fastened 

 together. The number of eggs in a cluster varies from very 

 few to about 150. The total number of eggs laid by one 



ENTOMOLOGY 



The first annual 

 eminent Entorao- 

 Nigeria has been 

 Jemmett, who was 

 1908-9, attached 

 Imperial Depart- 

 ture assumed the 

 in May 1909 and 

 headquarters a t 

 report covers a 

 months to Febru- 

 Fig. 10 

 the period under 



IN SOUTHERN NIGERIA. 



report of the Gov- 

 logist for Southern 

 received. .M r. C. W. 

 tor six months, in 

 to the staff of the 

 uient fjf Agricul- 

 duties of his office 

 estaUished his 

 Olokenieji. His 

 Ijeriod of nine 

 ary 1910. During 



Root Boi:er of Sug.ar-Cane. 

 review Mr. Jemmett .spent his time in 

 travel, and in becoming familiar with the conditions in the 

 agricultural districts of the country in which he is working. 

 Mr. .femmetl's report gives a sum- 

 mary of the important insect pests, and 

 emphasizes the need of an immense 

 amount of entomological work in South- 

 ern Nigeria. A classification of insects 

 according to economic concern is given, 

 and notes on a few of the most impor- 

 tant insects noticed in 1909. 



It is of interest to note that the 

 nature of the attack on several tropical 

 crops such as cacao, cotton, maize, 

 cocoa-nuts, etc., is the same as in the 

 West Indies. The insects are not identi- 

 fied, so it cannot be stated whether they 

 are of the .same species as the West 

 Indian forms. 



In addition to the annual report, 



Mr. Jemmett has issued a preliminary 



report on the insects affecting maize, 



a report on those observed on cotton, 



iLs (Calandra spp.). ^nd one on insects found on cacao 



in 1909. 



Maize seems to be attacked by two kinds of insects: 

 one the grain weevils, the other lepidopterous larvae. The 

 lepidopterous larvae would seem to be similar to the boll 

 worm {I/ili'it/iis o/jsoleta) and the corn ear worm {Laphy(/i)ia 

 frugipe.rda) in the manner of attack on the corn. The 

 caterpillars of the corn, in Southern Nigeria, tunnel into 

 the stem of the plant and the ripening ears of the grain, and 

 since they occur in large numbers they are able to cause 

 a very large amount of loss to the farmers. 



The grain weevils {Calandra granaria and C. ori/:ae) 

 are of very general occurrence in many parts of the world as 



