250 



THE AGRICULTURAL NEWS. 



August 1, 1914. 



INSECT NOTES. 



ROOT 



BORERS. 



lu the Aijrii-uUural A\'<rs tor Juir' 20 hist, (.see 

 Vnh XIII, p. 202) an article which had pieviouslj- appeared 

 iu a Jlartiuiipte newspaper was reviewed under the collective 

 heading of Insect and Fungns Notes. The article dealt with 

 certain experiments in ilartinique in the use of carbon 

 bisulphide in emulsion, for the control of soil-inhabiting 

 grulis which attack cacao and limes when these were planted 

 in lands formerly devoted to the cultivation of sugar-cane. 



The insect principally concerned was stated, Ijy Mons. G. 

 Bordaz, the author of the original article, to lie the 'larva 

 of a handsome beetle very common in our colony,' Diaprepes 

 famelicus. It was thought at the time that the review 

 was j)re})ared that the names Dia2)re2}es faiiielicus and 

 Exoplitltalmus fumeliciis were synony- 

 mous and that the ilartinique insect 

 would be the same as the Dominica 

 f)ne which lias recently lieen identified 

 as E. favielicus. 



Specimens recently received at the 

 Head Office of the Imperial Depart- 

 ment of Agriculture from Mons. G. 

 IVtrdaz prove to be the same as the 

 Barbados root borer (Diaprei^es abhrevi- 

 ains). 



A visitor to Barliados who is 

 interested in the cultivation of sugar 

 in Guadeloupe has recently informed 

 the Entomologist on the staff' of thi^ 

 ])epartnient that the Barbados rout 

 liorer i^ the same as the root borer 

 of sugar-cane in Guadeloupe. The local 

 name for this insect in that island is 

 'jacquot.' 



This information would seem tn 

 add these two localities, Martinique and 

 Guadeloupe, to the known distribu- 

 tion (if D. a/ilireviatus. 



E.i'opht/ialmus famelicus is a small, 

 plain, greyish weevil similar to, but 

 smaller than, the Leeward Islands root 

 borer {E. esuriens) and not at all, in 

 its colour and markings, like the beauti- 

 ful Diaprepes abi/rei'iatus. 



lit the same number of the Agri- 

 cultural News to which reference has 

 been made above, a note appeared Fit 

 mentioning the unusual occurrence of (about 2.V times Natural Size.) 



interest in adding another island to the list of those in which 

 this insect is known to occur. 



The many and variable forms of Diaprepes which belong 

 to the two species D. abbrei'iatus and D. fpevijleri are now 

 known to occur in Barbados, Grenada, St. Vincent, St. Lucia, 

 ilartinique, Guadeloupe, Domiiuca, Montserrat, Virgin Islandss, 

 St. Croi.x and Porto Rico. The range of variety among these 

 insects in all the islands mentioned .seems to be very great, 

 but it is possil)le that eventually they may lie found to Ije all 

 of one species. 



Exophthalmus esuriens is now known to occur in 

 Barbados, Dominica, Montserrat, Antigua, St. Kitts and 

 Nevis. 



E. esuriens in St. Kitts, attacking sugar cane, and m 

 Antigua and Montserrat on limes. 



It may be of interest to add that this insect has recently 

 (•Inly 1914) been found in Barbados. This appears to be the 

 first record of the occurrence of this insect in that island. 



It was found on an estate, where systematic collections 

 of Diaprepes abbreviatus were being made, by the boys 

 employed for that purpose. They stated in answer to ques- 

 tions, that these insects were found among the canes in one 

 field, but it afterwanl transpired that these lioys with their 

 eyes trained to search for Diaprepes had found theE.xophthal- 

 inus weevils among the plants in the labourers ground at 

 some distance from the canefields. 



The present record of Exophtlialrtius esuriens in Barbados 

 does not connect its presence with sugar-cane, but is of 



THE CITRUS ROOT NEMATODE. 



In the Journal of Atjricidtural Besearch issueil liy the 

 United States Department of Agriculture, an article by 

 Dr. N. A. Colib, draws attention to 

 the almost world wide-occurrence of 

 a nematode worm which attacks the 

 fine roots of citrus trees. This article 

 also gives the known facts of the life- 

 history of this worm, which has been 

 named Tylenchulvs seynipenetnins, Cobb, 

 and it presents several drawings illus- 

 trating the anatomy of the organism and 

 the nature of the injury caused by it. 



It appears that this nematode, 

 first discovered in California, has since 

 been recorded from Florida, Spain, Malta, 

 Palestine and Australia. It is not 

 known to attack any plants other than 

 citrus although carefid search has been 

 made for it. 



The adult female of Ti/lenchulus 

 semipenetrans is of sufficiently charac- 

 teristic appearance to be easily recog- 

 nised by a specialist in this group of 

 animals, but the larva and the male are 

 distinguished only with difficulty from 

 the same forms of other .species, which 

 are to be found in the soil in the 

 vicinity of citrus roots. Dr. Cobb 

 states that upwards 100 different species 

 of nematodes have been found by him 

 in examining material from various 

 parts of the world. 



Some of these forms are predac- 



eous on others and it is probable that 



3. Diaprepes abb7-ei>iatus, TuE Advlt the pernicious efi'ects of the most 



harmful species are somewhat mitigated 



liy the efforts of their natural enemies. 



The citrus root nematode is not capalile of independent 

 migratifin for any consideraVile distance. It is spread liy the 

 distriliution of infested nursery stock, and, in the field or 

 orchard, )jy the surface water of heavy rains. 



It has been found that a temperature of 140'F, is fatal 

 to this nematode, and as this is not a temperature which 

 injures citrus nursery stock, the practice of dipping in hot 

 water at about 140° should give a means of disinfecting such 

 material and preventing the spread of the nematode. 



The authoi states that it is too early to make positive 

 statements as to the amount of the injury caused by Tycen- 

 chulus seinipene trans l:)Ut that it seems to be a pest of which 

 citrus growers in all parts of the world will have to take 

 notice. 



