282 



THE AGRICULTURAL NEWS. 



AvousT 31, 1912. 



INSECT NOTES, 



REPORT ON 



A VISIT 

 PART L 



TO ST. KITTS. 



The Eatoniologist on the Staff of the Imperial Depart- 

 uent of Agriculture recently visited the Leeward Islands for 

 'Jie purpose of investigating the occurrence of insect pests 

 attacking sugar-cane. The primary object of the visit was 

 to make a study of the conditions prevailing in the cane fields 

 f>i a certain estate in St. Kitts where termites had occurred 

 at intervals for several 3-ears in sufKcient numbers to cause 

 a considerable amount of damage. 



The following notes are 

 abstracted from a report 

 on the visit to St. Kitts, 

 which was prepared by 

 the Entomologist and sub- 

 mitted to the Imperial 

 ( 'ommissioner. 



TKRMlTivs. The attack of 

 growing sugar cane by ter- 

 mites in est. Kitts ap[)ears 

 to be the only occurrence 

 vf this kind recorded. It 

 often happens that cuttings 

 ii.sed for planting are dama- 

 ged in the field before the 

 young shoots start, or 

 about that time, but on 

 this one estate in St. Kitts 

 sugar cane plants which are 

 reaching maturity, and ap- 

 proaching the season of 

 ripening are attacked by 

 these insects. 



On this estate, in 190G, 

 termites occurred in suffi- 

 cient numbers to cause the 

 lo&s of almost the entire 

 crop over an area of several 

 acres. In 1911-12 the 

 attack was made in fields 

 near those which suffered 

 fill the previous occasion, 

 but the area involved was 

 smaller than previouslj', 

 r.nd even on this many plants 



Vio. 6. Thk AV')htJ': Ani'. 



(,a) '^ueen; (b) nymph of winged female; (c) worker: ( 

 All enlarged. (From U.S. Dejit. Agric.) 



s:aped. 



It is also to be noted that, while in the attack of 190(i 

 (lee Afp-ii-ultural Xriv.<, Vol. VI, p 56), the termites 

 npjjeared to be the principal cause of injury in the infested 

 fields, on this last occasion this was not the case — extreme 

 drought, and a severe infestation of moth borer and root 

 fungus appeared t<' liave caused more injury than the attacks 

 of the termites. 



The fields which suffered severely in 1906 had since that 

 time been planted for two or three years in cotton, and as 

 ;i consequence the termites were greatly reduced in numbers. 

 'I'hey did not occur to such an extent as to attract attention, 

 and it was only liy careful search that even a few stools of 

 canes were found to be infe.sted. 



The species of termite concerned in this unusual attack 

 on canes has not yet been determined, but it is suggested 

 that it may prove to be TermeK Hani/ies. This species appears 

 ; 1 i>c a native of tropical America, extending its range as far 



north as Boston, Massachusetts and other localities in the- 

 same latitude. Although the insect has long been known to 

 attack the timbers in buildings and other structures, it doe.s- 

 not seem to have been recsrded as a pest of growing plants. 

 In spite of its general distribution throughout this part oi 

 the world, and the attention it has attracted, no nests of th& 

 species appear to have been discovered. 



The termite attacks on growing canes generally begin 

 above ground: apparently the insects often enter by means of 

 a borer hole at about the time that the lowest internodes 

 begin to ripen It often happen,? that the interior of the 

 cane is eaten out completely, and this in the case of every 

 cane in the stool, and of all the stools over a considerabk^ 

 area. Canes .so attacked often remain green, or at least 

 possess a few green leaves at the top, probably indicating 



that the termiteshave eater^ 

 out the cellular tissue con- 

 taining the sugar, but have- 

 not entirely destroyed the- 

 vascular bundles on the pre- 

 sence of which the conduc- 

 tion of moisture depends. 

 The roots of the canes- 

 are also often completely- 

 eaten out, nothing being: 

 left except possibly the- 

 extreme outer layer of 

 tissue, which the termites^ 

 cover on the inside witk 

 a peculiar cement-like sub- 

 stance, and thus form their 

 tunnels and galleries in tht- 

 ground. 



No definite nests of this- 

 insect have been found ia 

 the cane fields where these 

 attacks occurred, but on tht- 

 visit covered by the report 

 under consideration, the- 

 Entomologist discovered au 

 enlarged gallery in whick 

 there were several egg-lay- 

 ing females. These insects* 

 are not the true sexual, 

 females, but are the sup- 

 plemental queens devel- 

 oped probably from the 

 workers by special feeding 

 in a manner similar to 

 the production of a new queen in the hives of the honey b?e. 

 The galleries in which these supplemental queens' 

 occurred contained no eggs, nor were any galleries found in 

 which the very young larvae were being reared. The 

 different castes or forms of this insect which were found iu 

 these fields were workers, soldiers, and winged forms— all ol 

 which occurred both in the tunnels in the ground, and 

 within the tissues of the infested plants — and the supple- 

 mental queens which were only observed in underground 

 galleries. 



The galleries and tunnels of this insect have been found 

 in the soil to a depth of 14 to l.s inches; those contain- 

 ing the egg-laying females were about 8 to 10 inches below 

 the surface. 



A similar attack by the same species of termite occurred 

 in the grounds of the Head Ottice of the Imperial Department 

 of Agriculture at Barbados during 19 11- 12. This was like- 

 that in St. Kitts, the only difference being that these cane* 



1) soldier. 



