392 Journal of the Department of Agriculture. 



same method. ... I am fully couvinced that the sweetened poison 

 bait is the most eiiective method for controlling' this pest. Before my 

 arrival at Witteklip, one farmer had rolled part of a field of infested 

 mai?e with a heavy roller to save this crop, but only a few cater- 

 pillars were destroyed. I was informed by several farmers that this 

 insect pest had destroyed all the crops in Garntoos Valley, Humans- 

 dorp district, and during my absence a telephone message was 

 received from Hankey to the eflect that the caterpillars were present in 

 large numbers and were causing- extensive damage. 



" 1 made a careful investigation on the farm Kocklands, and 

 found that the caterpillars had come from the veld near the cultivated 

 fields. The owner of the farm informeil me that the damage had been 

 done so quicklj- that he had only noticed it three days before my 

 a rrival . ' ' 



The attack on potatoes is thought to be unusual. A newspaper 

 account of the outbreak stated that large fields of cauliflowers were 

 destroyed, but it appears that in this case the mysteiy worm was 

 confused Avith the small cabbage worm. It is conjectured that the 

 parent mystery worm moths came from the north-east. If the moths 

 that result from the present caterpillars take the same direction in 

 migrating', they will be carried out to sea. 



Action in Cask of Eecukrence. 



if in future an outbreak of the insect should occur in any part 

 of the Union, farmers whose crops or veld suffer should report at once 

 to their mag-istrate in order that this Department may be put in 

 possession of information bj^ which the severity and extent and 

 probable spread of the visitation may be judged. It is likely that 

 the caterpillars escape observation, or at least fail to arouse apprehen- 

 sion, until they are nearly f ull-g ro \vn . 'IVff and other sown grasses 

 in which the caterpillars are abundant should be promptly mown in 

 order to save them and to expose more fully the insects to their many 

 natural enemies. The grass may be expected to grow again and yield 

 a g'ood cutting later unless frost interferes. So far as the veld is 

 concerned, remedial measures are impracticable ; but for the purpose 

 of saving young maize, grain, or grass from worms which might 

 migrate into the lands from the veld or from already infested crops, 

 poisoned bait is efiicient. The bait may be made of bran or other such 

 food while still fresh. Grass is naturally the most convenient and 

 cheapest bait on most farms. The other necessary ingredients are 

 arsenite of soda (or other insecticidal form of arsenic), sugar or 

 molasses, and water. The preparations recommended are one pound 

 of arsenite, two pounds of sugar or two quarts of molasses, and 16 

 gallons of water with as much bran or finely cut grass as the liquid 

 will thoroughly moisten. Sixteen gallons are sufficient for 150 lb. of 

 bran or 200 lb. of green stuff. Bran bait is easy to prepare and to 

 spread. The bran should be sprinkled and meanwhile turned over 

 and over until it is uniformly moist, but not sloppy; when it is wetted 

 to the right consistency, it can be broadcasted so thinly that no stock 

 can pick it up. Green stuff is best wetted by immersing it in the 

 liquid ; it should then be drained. The bait can be spread over grass 

 land or in grain crops, but it is not often that a farmer will care to go 

 to the expense and trouble of baiting whole lands. However, the 

 baiting of entire fields is not an uncommon practice in the United 



