SECTION X." MinilOBS OF CONTROL. 143 



About 5c. per hundred nymphs is paid and a child will collecl) 

 400-600 per day. According' to Kershaw (1913 I. p. 6) 700,000 were 

 collected in this way at Brechin Castle Estate on 31 acres at a cost of 

 $11 per acre. The same method was in use in British Guiana {see 

 Williams 1918 B. p. 170-171). 



It is a much slower method than crushing the nymphs, but has the 

 advantage that some check is kept on the activities of the gang. Unless 

 the children are carefully instructed they will destroy Syrphid grubs as 

 well as nymph froghoppers. 



Destruction of the Adult Froghoppers. 



Hand Collecting. Both in Trinidad and in British Guiana children 

 have been employed at various times to collect and destroy the adult 

 froghoppers by hand. This is an extremely slow process and even when 

 they are abundant, it is seldom that more than six or seven hundred are 

 collected as the result of a day's work b^^ one boy, whereas this number 

 can be caught in a few minutes by the use of nets (see below). 



The sexes caught are in more or less equal proportions, a slightly 

 greater number of females is sometimes found, owing to the activity of 

 the males giving them more chance to escape. 



In some cases the insects thus caught are infected with green 

 muscardine fungus and allowed to escape to infect others. 



In other cases instead of collecting the adults, the growing point of 

 —the- cane is squeezed with the hand to destroy the insects sheltering in 

 the axils of the leaves (Carlee 1912 A. p. 271). 



Spraying. Spraying for adults with kerosene emulsion has been 

 '"recommended by Gough (1911 A. and 1911 C. p. 28) and ha« already 

 been discussed above (p. 142). It is worthy of more extended trial and 

 might be of value in small localised outbreaks. 



Light Traps. The adult froghoppers can be caught in great 

 numbers by means of light traps. On one occasion I captured 20,000 in 

 five traps in one night, and at Caroni in 1915 with 100 lamps the 

 captures reached 250,000 per night during the broods. 



The form of trap generally in use is shown in fig. 32 and consists of a 

 kerosene oil (paraffin) lantern, locally known as a hurricane lamp, placed 

 in the middle of a round tin pan of about twelve inches in diameter, in 

 which there is about half an inch of water with a little kerosene oil on 

 ihe top. 



