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THE AGRICULTURAL NEWS. 



May 24, 1913. 



INSECT NOTES 



ROOT BORERS AND OTHER GRUBS 

 IK WEST INDIAN SOILS. 



As was premised in the last i.ssue of the Agricultural 

 JS'ev'f, the above subject i3 continued in regard to the 

 lihinoceros beetles, and th? natural enemies of the different 

 soil-inhabiting grubs so far described in this series of articles. 



The rhinoceros beetles receive their common name from 

 the jiresence of one or more projections from the upper 

 surface of the the rax, or from the head and thorax. These, 

 ill most species, are mote conspicuous in the males than in the 

 females. 



The rhinoceros beetle of St. Uroix and Jamaica (Strate^/us 

 titanus). References: Agricultural J^'eivs, A'ol. XI, p. 346; 

 Jiulktin of t/w DepartiTient of Agriculture, Jamaica (Novem- 

 ber 1903), p. 250. 



Utratcjas titanus was first reported to the Imperial 

 Department of Agriculture a^ a sugar-cane pest in August 

 1912, by Dr. Longfield Smith, Superintendent of Agriculture, 

 St. Croi-x, Dani.sh West Indies. Subsequent correspondence 

 has brought out the following information with regard to the 

 insect in that island. 



In 1871, ^^tn.itegus titanus grubs were present in the 

 soil of Cine fields in St. Croix in ;<uch numbers as to cause 

 aeiinus injury, and in that year planters offered a price for the 

 grubs Dr. Smith writes that the grubs eat the roots of 

 sugar-canes, sweet potatoes and other plants, and in the case 

 of the cane they tunnel in at the base of the stools, and eat 

 their way up into the stalks of the cane, turning them into 

 hollow tubes. This was written with regard to the older 

 piant.s in August and September last. As regards the 

 attacks on the young plant canes, it is stated that the eyes 

 and the young roots are e.aten off and the grubs often tunnel 

 into the interior of the cuttings used for planting, resulting 

 in a germination in certain fields of not more than 20 per cent. 



The grubs appeared to be most abundant in August. In 

 September many adult beetlf^swere to be seen, and the larvae 

 were present in smaller numbers. 



Stratigus tifanus seems normally to be more a scavenger 

 that a direct pest on living plants The fields in which the 

 attacks on canes have been most severe were manured 

 with farmyard manure, largely made up from megass. Exami- 

 nation of megass heaps has revealed the presence of this 

 insect and the common hard back {Ligyrus tumidosus) in 

 considerable numbers. 



Dr. Sniith has made trials of poisoned baits for controll- 

 ing the attacks of Strategus and good results appear to have 

 been obtained with one of these in [■reliminary trials. This 

 was prepared by using migass, 100 lb , and l^ari.s green, 3 tt). 

 A handful of this mixture wus placed in a hole made with 

 a drill alongside each cane plant, .\fter an interval of 

 about a week the baits were examined, and a large number of 

 dead and dying grubs were found in and near to the poisoned 

 megass. This would indicate that a method of control ha.s 

 been found, and it only remains to determine to what extent 

 this method will be effective when carried out on a large scale. 



Strategvs titanus is considerably larger than any other of 

 the s[>ecies dealt with ir these articles The adult beetles 

 range from 1 inch to 1| inches in length, whilst the larva 

 attains a length of about 2h inches, and a diameter in it.-* 

 thickest part (if about iincli The thor;icic ptojections or horns 

 which are characteristic features in the adults of many 

 rhinoceros beetles, are represented in tbi.s species by very 

 inconspicuous tubercles. 



Slratff/us titavus ia recorded as occurring in Jamaica,, 

 where it has l>een found in the decaying wood of an orange 

 tree which was killed l.y attacks of the fiddler beetle. 



The Curator of the Experiment Station at Tortola 

 recently reported the occurrence of this in.sect in the Virgin 

 Islands, after having seen it in St. Croix. 



A large rhinoceros beetle is reported to have beeo 

 a serious pest of cane on a limited area in Porto liico, where it 

 caused injury in e.^jcess of that resulting from the attacks of 

 the Lac/inosteru'i sp. (See reference under Lnchnostirna sp. 

 in Porto Rico, above.) This rhinoceros beetle is probably 

 Strategus titanus, or a related .-"pecies. 



The rhinoceros beetles of coconut palms, in Trinidad, 

 (Strategus anachoretus). Tieferenee: Circular Xo. 5, Board of 

 Agriculture, Trinidad and Tobago. 



This insect attacks coco-nut palms in Trinidad, where the 

 larvae are said to live in rotten wood or decaying vegetable 

 matter. The adults, large beetles, .sometimes 2i inches in 

 length, tunnel into the base of young trees newly planted out. 

 The larvae sometimes occur in the .».oil of sugar-cane fields,, 

 where they attack canes after the manner ol Strategus titanus 

 larvae in St Croix. 



The attack liy the adult Strategus anachoretus or> 

 coco-nuts seems to be like that of the adult Tomarus (ntuher- 

 culatus on banana suckers, while its attacks in the larval 

 stage on sugar-cane appear to be more like those of the 

 larvae of Stj-atrgus titanus on sugarcane in St. Croix. 



At least five other species of hard backs of the sub fam- 

 ily Dynastidae are known in the Lesser Antilles, which may- 

 be of interest in this connexion. These are: — 



Cyclocephaii tridintata which occurs in Dominica anf'. 

 St. Lucia. It is fairly abundant in the former of these islands, 

 judging from the numbers collected from time to time. There 

 appear to be no records of its habits in either the larval or 

 adult stages. 



C gclocephala diniidiata is reported from Crenada, as 

 feeding upon the flowers and flower- buds of cotton, eating 

 the corolla and often injuring the essential organs. 



Cyclocephahi rinrentae \n St. Vincent, and two species 

 of Leucothyrcus, one occurring in St. Vincent and one in 

 St, Lucia are only known from the habits of the adultst 

 of feedina on the leaves of plants, especially cacao and cotton. 



The injury resulting from the feeding of any of the 

 adult beetles mentioned in these notes, is not severe. 

 Occasionally a few leaves may be eaten, or in some instances 

 the adults may tunnel into the tissues of the plants and 

 cause a certain amount of damag-t. The real danger from 

 these insects lies in their capacity for harm, while in the 

 larval or grub stage of development. In fact, in the case of 

 the root borers and the white grubs of the hard backs in tht- 

 group Melolonthidae, these may become -so numerous as to 

 cause really serious injury to crops before the adults 

 are known to the planters. This is because many of these- 

 adult insects are not attracted to light, and they hide in the 

 soil or among the foliage of plants during the day and thus- 

 are easily overlooked. 



Whenever a beetle of any sort occur.-, in such numbers as- 

 to attract the attention of the planter, he should at once 

 ask himself — Where does the larva of this beetle live, and ors/ 

 what does it feed' 



If it is a beetle of the weevil or hard back type, such as- 

 th» root borer or the common hard back, the larvae are almost 

 certain to be found under ground, either feeding among 

 decaying vegetalile matter, or in or im the roots of living- 

 plants; or, in the case ,of the weevil, it may be a borer in the 

 stems of trees or shrubs. 



