su 



THE AGRICULTURAL NEWS. 



October 5, 1918. 



INSECT NOTES. 



insect:;notes from porto rioo. 



The following notes are ab>tracted from papers by 

 Mr. R. T. Cotton, Assistant Entomologist, In.sular h^xperimeut 

 Station, Porto Rico. They are reproduced here, as being of 

 general interest in the British West Indies, with commeats- 

 on our local conditions. 



THE EGG-PLANT LACE-BUG. 

 The eggplant (So/amim melongena) is attacked by 

 several pests, the worst of which is the lacebug (Corythaica 

 mouacha, Stal.). This bug is widespread over the island and 

 attacks the eggplant wherever it is grown, causing heavy 

 damage when not controlled by spraying. It feeds normally 

 on the so-called wild egg-plant {Solanum ton-urn), and it is 

 on this plant that it is able to survive durint' the interval 

 between crops. So/aitiim ton'i-.m is one of the most abun- 

 dant weeds on the island, growing luxuriantly in all parts 

 and at all times, and it is undoubtedly owing to this fact 

 that the lace-bug is so abundant. If it were dependent 

 solely on the cultivated egg-plant for its food supply, it would 

 soon" die out, as the egg-plant is seldom grown at all times 

 of the year, even in the most favourable localities. 



The injury to the plant is occasioned by the feeding of 

 the nymphs and adult.s, which congregate in hundreds on the 

 undersides of the leaves, and suck the vital juices from the 

 plant. Their presence on the leaves is first indicated by the 

 appearance of small yellowish-brown patches, which growing 

 in size soon involve the entire leaf, causing it to dry up and 

 fall off. It is not an uncommon sight to see a whole patch of 

 eggplant entirely denuded of its leaves. The in.sect has a very 

 short life cycle, and multiplies so rapidly that, once introduced 

 into a field, it soon spreads to every plant. 



Control. This insect may be efifectively controlled by 

 a soap andwater spray, s B). of soap to 50 gallons of water 

 being a good strength to use. The plants should be 

 sprayed as soon after the appearance of the lace-bugs as possi- 

 ble, since it is much easier to control them then than later. 

 (Journal of tht Dcpartntait of Ag,riailtiin\ Porto Rico, 

 Vol. L No- 3, July 1917, p. 170.) 



Although the eggplant is not cultivated on a large scale 

 in the Lesser Antilles, it is grown in vegetable gardens by a 

 great many people who will probably be glad to know of such 

 a simple and easily prepared contro! method as a soap and- 

 water .spray. 



The lace-bug in these islands is to be found on wild plants 

 of the genus Solanum, and, a-s an aid to control, all the plants 

 on which this insect occurs should be searched out and des- 

 troyed for .some dist mce around gardens where the eggplant 

 is grown. 



SCALE-FEEDIXG HABITft UF P(M;T<> iac< - 

 MILLIPEDKS 



During investigations into the feeding habits of some of 

 the common niillip(5es of I'orto Rico, one was found to feed 

 on the purple scale (Lepidosaph,s l/eclcii) on citrus trees. 



This millipede is a large, dark, reddish brown form about 

 80 mm. (.3i inches) long, which has been identified as Rhincri- 

 cm (ir/'ortus, Saussure, which is recorded as occurring in seve- 

 ral West Indian i-slands— St. Thomas, St. Croix, Antigua, etc. 



These millipedes were observed to be feeding voraciou.sly 

 on purple scale on grape fruit. In the laboratory it was 

 found that they thoroughly cleaned otf the scales from 

 infested grape fruit twigs in a short time. It was ascertained 



from actual cour»t that one specimau consumed 2,000 scales- 

 in a period of three hours, and after a short rest resumed 

 feeding. 



Several small grape fruit trees which were badly infested 

 with purple scale were selected, and in each about a dozen 

 millipedes were placed. They at once commenced to feed oc 

 the scales, and at the end of two weeks these trees were clean 

 and free from scales and they remained clean for some time. 



Fig. 3. Millipede. 



These millipedes are not considered likely to be of any 

 great importance in controlling scale insects, but this is an 

 interesting note of a scale-feeding habit on the part of au 

 animal supposed to be a vegetable feeder. {Journal of tht 

 Department of Agriculture, VoTtf^ Rico, Vol. I, No. 3, July 

 1917, p. 175.) 



In all the islands of the Lesser Antilles millipedes occur 

 which are much like this one, if, indeed, they are not the 

 same species. They are often to be seen in cane fields, and 

 after rains they may be seen crawling in the roads. When 

 disturbed they curl up in a spiral. The accompanying 

 illustration may serve to give an idea of the general appear 

 ance of a millipede. 



SCALE INSECTS AND THKIR CONTROL. 



Circular No. 9, entitled 'Scale Insects and their Control', 

 issued by the Board of Commissioners of Agriculture, Porto- 

 Rico, gives an interesting popular account of scale in.sects, 

 what they are, how «they feed, and consequently, how they 

 injure plants, and mentions a few of commercial value, su'.h 

 as those which produce Cochineal, lac, from which shellac is 

 made, and a wa.K used in making candles in China. 



The following paragraph gives an account of the agencies 

 which work against the scale insects: -- 



'The scale insects -have by no means a calm and 

 undisturbed e.xistence, for they are beset by many 

 enemies. Many beetles of the Coceinellid family feed 

 almost exclusively on them, and liyraenopterous insects 

 deposit their eggs inside the scale, eventually causing 

 its death. In Porto Rico, the large brownish-black milli- 

 pede, or 'gongoli' feeds voraciously on the purple scale of 

 the citrus trees, and should be encouraged and introduced 

 into the groves. Birds also feed to some extent on scales, and 

 should be likewise protected and encouraged. Various oene- 

 ficial fungi wage a deadly warfare against scale insects, and in 

 Porto Rico the" so-called red and black fungi are extremely 

 effective in keeping down the scales in citrus groves. To 

 provide favourable conditions for the growth of the.se fungi, 

 it is necessary to grow wind-breaks all through the groves. 

 These wind-breaks will do away with the strong winds which 

 are unfavourable to the growth of fungi, and ordinarily the 

 scales will be keiit pretty well in check.' 



It is stated that most scale insects may be kept in check 

 by means of control sprays, and the following formula is given 

 as being the cheapest and most effective spray yet devised 

 for use in Porto Rico. 



The Government formula for its preparation is aa 

 follows: — 



