THE CAMPAIGN AGAINST PHYTALUS S.MITHI. 1 03 



insects, and is required to patrol the section allotted to it on a deptli of 7I a mile at 

 least once in each night, and to collect insects found occurring on this area. The 

 gangs are regularly inspected by a travelhng inspector, when attendances are 

 verified, captures of insects checked, and the general working of the gang examined. 

 As the result of work on these lines during two seasons there appears reason to believe 

 that the rate of outward spread is becoming considerably reduced. 



The collection of beetles during busy seasons affords part time employment to 

 large numbers of people, and at such times the actual number engaged may total 

 several thousands. The largest number of beetles captured on any one night 

 amounts to 4,600,000, which was recorded on 12th January 1919. Emergence of 

 beetles usually takes place in flights, large numbers appearing simultaneously for 

 a short period and then rapidly diminishing. It is usual for two or more flights 

 to be recorded in one season, and on occasions when beetles are numerous it is 

 remarkable, after nightfall, to observe the country-side dotted with the lanterns 

 of collectors. 



The transport of the beetles from the points of collection gave rise some time ago to 

 fears concerning possibilities of reinfestation owing to their escape from unsuitable 

 containers. A special form of container, intended to preclude the escape of captured 

 insects deposited therein, has in consequence been devised and efforts, made to 

 induce all persons engaged in the work of beetle collection to provide themselves 

 therewith. 



Daily returns of captures of beetles and of larvae are supphed to the Head Office ; 

 by means of these, detailed control of the work is maintained, and it is found possible 

 in this way to detect readilv locahties which show signs of being especially heavily 

 infested and if requisite special attention can then be devoted to them. 



From the outset the collection and destruction of larvae, by digging them out of 

 the soil in badly infested areas, has formed an essential part of the control measures 

 adopted. As at present conducted, it is principally combined with survey work 

 and is carried out during those months of the year when beetle emergence is at a 

 minimum and the larvae are attaining full growth, viz., May to August. With the 

 gradual spread of Tijpliia parallela, the introduced parasite, it has been found 

 advisable to restrict the destruction of larvae in locahties in which this parasite has 

 established itself, as the indiscriminate destruction of larvae in these circumstances 

 may do more harm than good, owing to the risk of destroying those that are para- 

 sitised. 



Census work in the infested area has been systematically carried out for some 

 years past. Under this method in every field in the zone 10 to 15 trial holes of a 

 depth of 8 inches are dug in every acre, the larvae found in each hole are counted, 

 and an infestation rate per acre is worked out. The results are subsequently 

 tabulated in the form of a plan, a system of tinting being adopted to indicate varying 

 degrees of infestation. Following this, orders are issued to estate proprietors to 

 dig out the larvae on fields which show more than 20,000 larvae per acre. The 

 prescribed fields are subsequently investigated again after the digging operations 

 have been completed, and if the work has not been satisfactorily performed, the 

 Department of Agriculture is empowered to repeat the process and to charge the 

 estate owner with the cost. 



