52 Two Scoliid Parasites 



In view of experiments in introducing this or other species of Tiphia 

 for the control of Melolonthid grubs in other West Indian Islands 

 and perhaps elsewhere it may be of value to give the results of the 

 writer's experience in Barbados. The most obvious procedure is to 

 dig up and transmit the cocoons, but success has not ensued from the 

 practice of this method. Large numbers of cocoons have been dug out 

 under the writer's personal supervision. They have been exposed as 

 little and handled as carefully as possible, kept on or in soil or in various 

 receptacles, in different degrees of moisture. Always the number 

 emerging has been disappointingly small, with no observed indication 

 of the cause of failure. Under each condition tried, except when the 

 cocoons were completely buried, a small percentage emerged, while 

 the rest of the cocoons when opened showed larvae, pupae or imagos 

 dead and dry. Buried cocoons failed altogether. It seems most 

 probable that mechanical injury is inflicted in the disturbance involved 

 in digging up and transporting the cocoons. The tenderness of Lepi- 

 doptera at the same stage will occur as an analogy to the entomologist. 

 It scarcely needs to be added that shipment of such cocoons, in cool 

 storage or by parcel post, has not been attended with success. 



The method by which living material was eventually landed in 

 Mauritius was as follows: Wardian cases with a sugar-cane stool 

 established in each were stocked with healthy Phytalus grubs, and 

 Tiphia imagos, male and female, were introduced and fed with syrup 

 and water. Many of the grubs were later found to be parasitized, 

 others had completed their development and commenced a new gener- 

 ation of Phytalus in the cases. Fresh grubs were introduced as fchey 

 were obtained up to the date of shipment. The only information I have 

 received was that from this material wasps were obtained in Mauritius 

 which laid on Phytalus grubs in the insectary there. For introductions 

 where the time taken in transit does not exceed the length of the life 

 cycle of Tiphia it would be sufficient to have a number of boxes con- 

 taining grubs in soil, to cover each for a few days with a cage of mosquito 

 netting within which Tiphia imagos could be confined, and then to 

 remove the cage and transmit simply the boxes with the parasitized 

 grubs. Probably success might be attained in sending cocoons, provided 

 these had been formed in the insectary in small boxes of soil, match 

 boxes say, so that they could be sent with a minimum of disturbance. 

 In any case, unless the indication that the parthenogenetically produced 

 wasps are males should fail to be confirmed by further experiments, it 

 will be necessary to send a sufficient amount of parasite material to 



