426 



THE AGRICULTURAL NEWS. 



Decembee 30, 1916. 



INSECT NOTES. 



PESTS OP SUGAR-CANE IN BRITISH 



GUIANA. 



II. 



In the last i.ssue of the A'jrictild/r'il 3"e"'.s, the first 

 part of ihis article, which deals with the control of sugar-cane 

 pests, concerned the small black hard back. The present 

 part of the article has regard principally to the borers. 



THE SMALLER MOTH BORERS {DiatTde'i sacc/iaratis and 

 D. cand/a). These insects still continue to be the most 

 important of the sugar-cane pests, in spite of the great 

 advance in the collection of egg masses and caterpillars. 

 Mr. Moore considers that these pests will not be controlled 

 until adequate, persistent, and systematic work can be kept 

 up, throughout the end year grinding season, at which time 

 the campaign against them ought to be hardest. The 

 shortage of labour, however, allows of practically no work 

 being done during the three months of the heavy grinding 

 season (October to December), so that the borers increase 

 rapidly in the young fields during and immediately after 

 this period. The clearing and burning of large continuous 

 areas brings about a deficiency of parasites, as ilr. (^)uelch 

 has pointed out, and this explains the usual heavy infesta- 

 tion of youDg fields by borers during the early months of 

 the year. 



The collection of egg masses has grown from nearly 

 180,000 in 1913 to over 500,000 in lt)U, and over 812,000 in 

 191."). But the greatest possible benefit was not always derived 

 from the egg collecting, because adec^uate provision was not 

 made for storing the clusters and distributing the parasitized 

 ones in the fields. The numbers of caterpillars collected 

 dropped from 25,-583 987 in 1913 to 20,888,012 in 19U, 

 and 19,136,345 in 1915, but this decrease was more than 

 offset by the great advance in the collection of egg-clusters. 

 In discu.ssing the treatment of replants, Mr. Moore recom- 

 mends that the eggs be collected and the borer cut out from 

 the old bank spring liefore the plant tops start to shoot;, since 

 the plant top spring is almost invariably attacked if the borer 

 in the old bank spring is left uncontrolled. These reports 

 make mention of six new food-plants, four of which belong 

 to the genus Paspahim, including P. ;/ra<:ile a,nd P. I'lryatuin. 

 These are all grasses growing in moist conditions, except 

 P. virgatum. The remaining two food-plants given are 

 a sedge (Cypetua .sp.) and another water grass, Panicum 

 elephantipea. This seems to show that among wild plants 

 D. saccharahs has a preference for more or less aquatic 

 grasses, and may indicate that wet weather might be favour- 

 able to this borer in the cane fields. Mr. Moore has not 

 studied the influence of weather conditions on these borers 

 enough to be able to make any positive statements. He has 

 found, however, that during dry periods the egg-clu.sters 

 collected were very small, whereas the average size of the 

 clusters become normal as soon as the rains started. 



Among predaceous enemies of the IJiatraea larvae are 

 mentioned a fiy (I)iptera, family Stratiomylidae, Sarffux sp.), 

 an undetermined beetle larva (Coleoptera, family ('arabidae) 

 and a Pseudo-scorpion. These, however, are not of special 

 importance in the control of the borer. 



THE GIANT MOTH BORER (CaSttlia Ucus). 



This pest may now be considered as under control on 

 most estates. The good work against the moths and cater- 

 pillars must be kept up .systematically and persistently, since 

 control does not mean fliniination. 



The campaign against the grubs in 1915 was harder 

 than ever, especially on the three worst infested esta'tes, and if 

 this work is kept up in the future, there is no doubt that the 

 control of Castnia will be as effective as it is on the others. 



TERMITES OK Wl >OI>-ANTS. 



Wood-ant infestation continued to decrease as a result 

 of the persistent and systematic destruction of nests. 



It is urged that nests be destroyed not only from cropped 

 fields, but from growing canes up to eight or nine months old, 

 since nests are often built upon the cane stems and the removal 

 of these nests would further helji to check the breeding of 

 this pest. 



THE LARIJEI; HAKI) BACK. 



Tills reddish-black hard back {Lt/(iyrus ebenus) caused 

 slight injury to cane stools both in 19ii and 1915. It was 

 found only in certain fields adjacent to savannah lands 

 covered with the sedge (Cyperus sp.) one of its native food 

 plants. This in-ect will require watching. 



FROG-HOl'i'EK. {l^oi/uispis jllai'ilaleta). 



The frog-hopper is an insect that must be carefully 

 watched to prevent its becoming a serious pest. It is found 

 on grasses near the coast and in abandoned cane fields. 

 Mr. Quelch discovered that the larva of a fly preys upon 

 the frog-hopper nymphs. This was found to be Salpingngaster 

 >ii(/rn, which attacks the frog-hopper in Trinidad. 



Mealy-bug was not very prevalent, but caused some 

 trouble on a few estates. Aspidiotus xaixhiri and Orthe:ia 

 proelonga are also mentioned as having occurred, the former 

 on poor stools, the latter on cane blades. 



LEAF FEEDERS. 



The grass-looper {Mods repmida), and the rice-worm 

 (LapliyyDciifrugijjcrda) are mentioned as doing local damage, 

 but a serious outbreak was prevented in each case by 

 collecting egg-clusters or picking the caterpillars. 



The brown locust (Schutocerca pil/ens) was abundant on 

 one estate in 1915, but was soon controlled by collecting. 

 The green grasshopper Conocepk'iloides taarillosa is also 

 mentioned, but was not important. A small brown 

 Chrysomelid beetle (Myochrouf ai-'iiatu.<) was fairly plentiful 

 on .several estates in 19 1 4- during the rainy season. These 

 beetles hide in the earth, or in the young shoots in which 

 they eat holes. 



J.C.H. 



Intercepting the Argentine Ant.— An article 



under Insect Notes sometime ago dealt with the Argentine 

 ant and the methods of controlling it, showing how nece.ssury 

 and diflicult these were, and how destructive this domestic 

 pest is in the Southern States of America and in South 

 rtuierica ai.so. In the rupuit on the I'lvisiou of Piaut luspcj- 

 tion at Honolulu, Hawaii, an account is given of how the 

 prompt discovery and extermination of a colony of these ant.s 

 which came for the Pacific coast of America with a .shipment 

 of plants, kept out from Hawaii a jjest which is becoming 

 a great nuisance in California and other i)laces, as already 

 stated. In regard to the present instance of interception, it 

 is stated that some ants were seen running about the cases 

 which contained the plants. The colony, however, was not 

 in this particular ca,se, and the whole shipment had to be 

 examined Ijeforo eventually the colony was discovered in 

 a corner of a box of carnation plants. This bo.x and 

 another which also showed a few ants were wrapped in ■11 

 tarpaulins and fumigated overnight. Luckily the whole 



