100 F. W. DRY. 



At least eight species of parasites, some Hymenopterous, some parasitic flies, have 

 been reared from material from the field at Kabcte. 



Little success in controUing the caterpillars has been obtained by spraying. In 

 May 1919 a number of spraying experiments were carried out in which strong Paris 

 green did produce some results. The Paris green was used at the high rate of 3 lb. 

 to 40 gallons. This was combined with (a) soap, {b) resin-washing-soda sticker, 

 (c) lime, (d) lime and sticker. With these four plots were sprayed side by side, and 

 subsequently some small dead caterpillars were found, the caterpillars in the field 

 being mostly only about half-grown. Dead caterpillars could not be found on un- 

 sprayed control areas. About ten days after spraying there was a great difference 

 between all these four plots and adjacent control areas. On the Paris green plots 

 little damage could be seen as one looked across the field ; on the controls the cater- 

 pillars had retarded the growth considerably. A sharp line was seen between sprayed 

 area and control. Later, the weather being damp, the control areas caught up with 

 the sprayed parts of the field. 



At other times spraying experiments with Paris green against larger caterpillars 

 have not met with success. One planter, who did not supply full data, reported 

 success with Paris green and lime, but the position is that one cannot recommend 

 spraying to planters. 



The method of combating the caterpillars by " roping " was devised by Mr. J. 

 McDonald, a Lumbwa settler, whose description is now quoted : — 



" A rope, 40 yards long and about one inch in diameter, held by a boy at each 

 end, is dragged through the flax, the infested area being gone over from three to six 

 times a day. If necessary more than one rope is kept in action at once. The rope 

 should not be held too tightly. The boys use the same tracks each time and very 

 little mechanical injury will have been done to the crop. The method is continued 

 for several days, until the caterpillars have disappeared." 



Here it is interesting to note, though the principle is not the same, that Dutt* 

 in India, speaking of the caterpillars of Phytomeira oHchalcea in peas, says, " Dragging 

 a rope, moistened with kerosine and turpentine, over the crop drives away the 

 caterpillars. Even if they go into the neighbouring fields the crop is saved." 



This roping method of ^Mr. McDonald's has been tried by quite a number of flax- 

 growers. Their reports have varied. Some have said it was entirely successful, 

 others that it was no use. Success, however, was reported in a sufficient number of 

 cases to suggest that the method was of some value, and a week on farms in the 

 Nakuru district, in June 1920, gave the opportunity of applying the tests to this 

 method now described. 



The method adopted was to obtain an index of the number of caterpillars in a 

 flax field where roping was in progress and then, four days later, to obtain another 

 index of the numbers present as a test of the result of roping. These numerical 

 estimates were made by walking slowly through the flax and counting the number 

 of caterpillars seen in five minutes, several such counts being made on each occasion. 

 The counts were made by the same people each time, in the same part of the field, 

 and at the same time of the day. 



The results may be summarised as follows : — 



Field No. 2.— The seed-bolls were just forming on the flax. Caterpillars were quite 

 numerous. Just a very few had formed cocoons. After four days roping with heavy 

 ropes about an inch in diameter the caterpillars were only a quarter as numerous as 

 when the first count was made. There were a few more cocoons than previously, 



* Report of the Proceedings of the Second Entomological Meeting, held at Pusa on the 5th and 

 12th February 1917. 



