298 



THE AQRICOLTURAL NEWS. 



September 14, 1912. 



INSECT NOTES. 



found iu the soil near cane stools attacked by root borer. 

 This weevil, wliich is of the same general shape as, and 

 slightly smaller than, the root borer weevil in Birbados, is 



Fig. 0. Geub of 

 Hardback. 



REPORT ON A VISIT TO ST. KITTS. 



PART II. 



THE HARDBACK. The Small brown haidbuck occurs in 

 considerable numbers in cane fields and other cultivated land 

 in'certain districts in St. Kitts. 



This insect has been identi- 

 fied, through the courtesy of 

 Mr. Guy A. K. Marshall, Scienti- 

 fic Secretary of the Entomologi- 

 cal Research Committee, as Lach- 

 nosterna patruelis. The grubs 

 of this species are of the typical 

 form of the white grubs or hard- 

 back grubs, while the beetle is 

 of the usual hardback form, but 

 considerably smaller than the 

 ordinary hardbacks. 



The occurrence of these insects 

 in abundance in the sugarcane 

 fields of St. Kitts is of interest 

 in view of the importance of 

 .similar pests in other countries. 

 In Mauritius, serious losses have 

 been oceasioneJ by the attacks of Phi/talus smitld which 

 is the same insect as that known in Barbados (see Agricul- 

 tural Neios, Vol. XI, p. 90) as the brown hardback. In 

 Porto Rico another species of Lachnosterna occurs as a pest 

 of importance in sugar-cane fields; and in other countries 

 related species of insects are attracting attention either 

 because of the injury they are known to cause, or on account 

 of what they are suspected of being capable of doing. 



The brown hardback in Barbados is parasitized by 

 a small black wasp which is probably responsible for keeping it 

 in check. In St. Kitts a wasp related to the Barbados species 

 was observed in the cane fields and a hardback grub was 

 found with a larva of a hymenopterous insect attacking it. 

 This is suspected to be a parasitism similar to that known to 

 occur in Barbados, but the relation between the wasps observ- 

 ed in the fields and the parasitic grub attacking the hardback 

 larva has not been proved. 



THE ROOT BORER. The root borer discovered in the 

 sugar-cane fields in St. Kitts appears to be of a different 

 species from that which occurs in Barbados, but in its manner 

 of attacking sugar cane it is very similar, and the grub is 

 much like the larva of Diaprepes abbreviates. 



Fig. 10. Eggs of Root Borer. 



In several different localities these large weevil grubs 

 were found tunnelling in the underground stem portion of 

 the cane stool. The adult of the root borer is not known 

 but it is believed to be a greyish-brown weevil which was 



Fig. 11. Root Borer, Grub (on left) and Perfect 

 Insect (on right). 



quite common in its occurrence in St. Kitta-Nevis, Antigua 

 and Montserrat, wher^ it is often to be found hiding amongst 

 the leaves of such plauts as castor and pigeon peas, which 

 grow along the borders of cane fields. This adult insect has 

 previously been kiinwn largely on account of its habit of 

 feeding on the leaves of limes and otlier Cilrus plants. If the 

 connexion between this weevil and the root borer grub is 

 definitely established, it may 

 prove to be a more serious 

 pest than has been suspected. 

 The fact that these beetles 

 are fairly abundant would 

 indicate that their larvae 

 must have some food plant 

 other than sugarcane, since, if 

 this were the only food plant, 

 the attacks would have been 

 discovered before this time, 

 while the relation between the 

 weevil and the grub would 

 have been sooner suspected. 

 The methods of control sug- 

 gested in the report for the 

 root borer and the hardback 



grubs are the ."ame as those Fig. 12. Damage Done to 

 suggested for the control of Sugar-cane by the 

 termites, which have been Root Boeer. 



mentioned already. 



Zalophothrix mirum. — Mr. J. C. Crawford, Assist 

 ant Curator, Division of Insects, United States National 

 Museum, described and named Zalophothrix mirum when 

 this useful parasite was found to be exerting a very material 

 control over the black scale (sSaissetia nigra) on cotton in 

 Barbados. 



In a note included in Descriptions of New Hymenoptera, 

 No. 3 {Proceedings of the United States National Museum, 

 Vol. 41, pp. 267-82), Mr. Crawford states that Z. mirum is 

 a synonym of Lecaniobius cockerelli, Ashmead. 



This insect will therefore be called by the latter name, 

 in future, in the publications of this Department, the name 

 being followed by the words 'Zalophothrix mirum' placed in 

 square brackets. 



Note. — The insect to which Figs. 10, 11 and 12 refer is 

 t'l ■ .lugar-cane root borer found in Barbados (Diaprepes ahbre- 

 viiitus), and probably not that of St. Kitts which forms the 

 subject of the article. [Ed., A.N.] 



