122 



of individual trees. This fact renders control difficult, as, if the 

 aphid is not killed within less than a week from hatching, the damage 

 to the crop is practically accomplished. The newly-hatched aphid 

 attacks the developing leaves and fruit-buds, causing the leaves to 

 curl so that the insects within are protected against spraying. The 

 stem-mothers give rise to several generations of parthenogenetic 

 females, and during the warm weather in June winged females appear 

 and migrate to an intermediate host. No aphids can be found on the 

 trees from this time until about the middle of October, when winged 

 viviparous females appear on them. The identity of the intermediate 

 host is uncertain, but aphids have been found on Careless Weed, 

 Amarantus retroHexus, at the time the viviparous females appear. 

 Winged males appear soon after the winged females. Egg-laying 

 begins with the first hard frosts, towards the end of November. 



In order to destroy the sexual females before they oviposit, an 

 autumn spraying between the 15th and 25th of November was tried, 

 this time being also a convenient one for the grower in other ways. 

 •Good results were obtained with 4 per cent, crude oil emulsion, and 

 in another case, distillate emulsion 3 per cent, and black leaf 40, 

 6 oz. to 100 U.S. gals. (83 gals. Impl.), used on about 200 trees also gave 

 good results. An application of 12i per cent, crude oil emulsion late in 

 December was as effective as the spring treatment. 



In the autumn of 1914 it was proposed to use the 12| per cent. 

 crude oil emulsion as near the 25th November as convenient, and by 

 this means, not only to destroy the sexual females of the purple aphis, 

 but also the eggs of the green aphis, of the tussock-moth, San Jose 

 scale, etc. The same spray gave excellent results against Aphis 

 prunifoliae (prune aphis) and Eulecanium armenaicum (brown apricot 

 scale) in 1913. In the case of prune trees, this need only be repeated 

 every three years, and possibly only every other year in the case of 

 apples. Growers are advised to make their own crude oil emulsion, 

 as it is cheaper and more effective. The paper concludes with the 

 following two formulae : — 



(i) Crude oil emulsion formula. Place 88 U.S. (73 Impl.) gallons 

 of water in the spray-tank and add 1 to 2 gallons, depending 

 on the softness of the water used, of liquid soap diluted with about an 

 equal amount of water ; agitate until thoroughly mixed and then, 

 with the agitator running, add 10 U.S. (8| Impl.) gallons of crude oil. 



(ii) Whale oil soap formula. Slice and dissolve 10 lb. whale oil 

 soap in not less than 10 U.S. gallons of water by boiling ; add this to 

 about 10 U.S. gallons of water (already in the spray tank) ; thoroughly 

 agitate and add enough water to make 90 gallons ; then add 2 lb. 

 caustic soda (concentrated lye) dissolved in water, and with the agitator 

 running add slowly 10 U.S. gallons of crude oil. 



Urich (F. W.). Entomologist's Report. — Minutes of the Meeting of the 

 Trinidad Bd. Agric. no. 9, 20th November 1914, p. 45. 



In the Toco district, Steirastoma depressum (cacao beetle) and 

 thrips were present in small numbers in isolated spots in exposed 

 positions. In the Sangre Grande district, thrips showed a tendency 

 to increase and spraying would be advisable in dry weather. At the 

 beginning of the month, no signs of froghoppers, Tomaspis saccharina, 

 were to be seen at Esperanza Estate. 



