202 



THE AGRICULTURAL NEWS. 



June 30, 1917 



INSECT NOTES. 



Meanwhile the colieation of adults seems to be the only 

 practicable method of control at the present time. 



The Antigua brown hard back was mentioned in the 

 Agikaltwal News for May 5, 1917, and some of the control 

 measures suggested last year by Mr. Billon were given. No 

 reports of this pest have been received so far this season, 

 so that nothing further can be .said about it for the present. 



J.C.H. 



SOME SOIL GRUBS IN THE WEST 



INDIES. 



In the last issue of the Agricultural A'etcs there were 



.some notes on root-borer grubs under the above title, and 



additional notes on the subject of hard backs were promised 



for this issue. 



The beetles known as hard backs in these islands belong 

 to the family gcarabaeidae, and the different species of these 

 beetles are grouped for ihe most part under two of the 

 sub-divisions of this family. I'lit/talus sniithi and the species 

 of Laehnosterna belong to tlie Melolonthids, the larvae of 

 which are root-trimmers; while the common Ligyrus 

 tuMu'osus, and species of Cyclocephala, Strategus and other 

 related genera are included under the Dynastids, -some of 

 which are scavengers in the larva) stage. 



A reference to the Agricnltvral News, Vol. XII, No. 290, 

 p. 186, will give the classification, distribution, and habits of 

 the grubs and adults of the commoner species of hard backs 

 occurring in the West Indies, and from this list it will be 

 seen that som« of these species are quite local in their 

 distribution, and are found in only one or two Islands. This 

 local distribution is especially noticeable in the case of the 

 genera Laehnosterna and i'yclocephala. The systematic 

 relationships of the species of Laehnosterna and allied genera 

 occurring in the West Indies have never been thoroughly 

 established, and the Imiierial Bureau of Entomology in 

 London has recently asked for as large a series as possible of 

 these beetles from the various islands in order to facilitate 

 the further study of this group by experts. These beetles 

 are still emerging from the soils in which as grubs they were 

 feeding on the roots of such crops as sugar cane and Indian 

 corn, or on decaying vegetable matter. With the well-known 

 exception of Ligyrus tumvlosus, the common blackish-brown 

 hard back, they are not usual. y attracted to lights but must 

 be sought out in the fields at night. During the day they 

 hide in the soil, or among the leaves of plants growing near 

 the cane fields, and come out at night to feed on the leaves of 

 plants. 



References have often been made to hard-back grubs and 

 beetles in the Agricultnrnl i\''(;(/'.s,and an account of the vaiious 

 species can be found in I'aniph'et No. 73, mentioned in the 

 last issue in connexion with root borers. The two most 

 serious pests at the present time are the Barbados brown 

 hard back (Phytalus sinithi^, and the Antigua brown hard 

 back, which is an unidentified species of Lachnosterny. Phy- 

 talus is very common in some districts of Barbados this 

 season, and a vigorous caiupaign is being carried out on 

 some estates. The adults are being collected by the thousands 

 in the fields at night by labourers carrying lights, and vessels 

 in which to put the beetles. 



In the last Annua! Report of the Barbados Department 

 of Agriculture, which was reviewed in the Agrindtural News 

 for May 19, 1917, reference was made to the fact that this 

 brown hard back seems to be controlled by its parasite 

 (7\),hiafarallela) in some localities, while there ars other 

 di.stricts where Phytalus occurs without its parasite. Efforts 

 are being made to introduce Tiphia into localities where it is 

 needed, but it will be some time before it becomes established. 



SLUGS. 



Within recent years slugs have been attracting consider- 

 able attention in these islands as pests of many estate and 

 garden crops. Reports from some of the Agricultural Officers 

 show that the 'leather jacket', or the 'palute' (as the slug is 

 sometimes termed) is most in evidence as soon as the first 

 rains have fallen in May or June, but that it is pre.sent more 

 or less all the year round 



FOOD- PLANTS. In Dominica, besides attacking such crops 

 as sweet potatoes, yams, tanias, cabbage?, melons, cucumbers, 

 ground nuts, etc., these molluscs have also injured Para 

 rubber seedling.>s, and stripped young budded citrus plants. 

 In Mon'serrat they have recently been reported as a pest of 

 cotton, being abundant on a small experiment plot at the 

 Botanic Station The above list of food-plants is by no means 

 complete, but is fairly representative of many of the islands. 

 HABITS. Slugs like places where the soil is kept cool 

 and moist by rank growths of wild or cultivated vegetation, 

 by mulches, by heaps of weeds or trash, by flat stones or 

 boards. They hide in such places during the day and come out 

 after nightfall to feed, returning to their hiding places in the 

 early morning. Tlie eggs are laid in damp situations and a 

 large number of individuals may be produced in a com- 

 paratively small area. When these have grown enough they 

 make a rai<l on the nearest vegetable gardens and play havoc 

 with the tender young plants. These outbreaks occur 

 suddenly and are fif short duration, but are severe while they 

 last. 



Mr. Robson, the Curator of the Botanic Station in 

 Montserrat, has made some notes on a recent outbreak of 

 this pest which took place on a -]-acre experiment plot at the 

 Station. In this instance, cotton followed sugar cane, and 

 after the cane stumps had been dug out in March the trash 

 was ranged and the space between the rows flat-forked. 

 The seeds were planted on April 6, and a week later 

 it was noticed that the young seedlings were being in- 

 jured, and slugs were suspected. Beginning on the night 

 of April l.'l, collections were made by lamplight nearly 

 every night till May 10, by which time all further danger 

 from the slugs seemed to be over. During this period a total 

 of 8,343 slugs was collected on the |-acre plot, and it 

 was noticed that there was marked inert ase of slugs after 

 rain. 



This is the first time that cotton has been recorded as 

 a food-plant of slugs, and it was not eaten very readily. 

 Mr Robson foun<l that the young stems were .sometimes 

 eaten through below the seed-leaves and the leaves themselves 

 left on the ground, while on older plants the skin on one 

 side of the stem might be eaten away. 



Control Mea.sures. 

 There are no really satisfactory remedies against slugs, 

 but the following are some of the methods of control that 

 have been omplciyed in different places 



ERAmiATioN OF BREEDJNc PLACES. As mentioned 

 above, slugs usually breed where the soil is kept moist by 

 a covering of vegetation. The weed covered banks of open 

 drains or ditches are often favourite breeding places, and 

 such places should be thinned out and the soil raked over 

 to expose any eggs hidden there to a drying out in the sun. 



