Economic Iniiwrtancc of the Parasites of Coccid^. 225 



hood of Cambridge as well as to the United States, and in 

 the locality I refer to the pest is satisfactorily controlled by 

 the parasite. If the parasite is not fonnd in other localities 

 where the scale is injurious it should be introduced there. 

 Considerable difficulty has been experienced in the attempts 

 to distribute the predaceous enemies, but in the case of the 

 internal parasites, the task is much simpler, and success 

 will be easier to attain, for it is only necessary to transmit 

 a small plant bearing a few parasitized Coccidm, From my 

 work on this species of parasite I am led to believe that 

 the Encyrtinsa are remarkably tenacious of life in their 

 early stages. 



Judging, therefore, from my own observations on the 

 subject, supported as they are by Mr. Johnson's remarks 

 quoted above, it is clear that, from tlie point of view of the 

 cultivator, it is of the utmost importance that, previous to 

 any attempt to destroy the Coccidte, it should be ascer- 

 tained whether internal parasites are present or not. If 

 they are found in large porportion, then the application of 

 a remedy should be abandoned. If they are present in a 

 smaller proportion then time should be allowed before any 

 insecticide be used, so that the parasites may emerge from 

 all those individuals containing them, so as to allow the 

 beneficial creature to be perpetuated and increased. After 

 the emergence of the flies, then the Coccidse, if any such 

 there be, may be killed by using those insecticides which 

 are especially adapted to the particular case. 



An impression still seems to prevail in this country that 

 the parasites of scales are of little importance from an 

 economic point of view. Mr. F. V. Theobald,* in a report 

 just issued, recommends the importation of Coccinellid 

 predators to destroy scale, and then remarks : " A few 

 minute IcJmeumonidiB also feed on certain species of scales, 

 but unfortunately our worst pests seem immune against 

 them." By the term "IchncuvionidcV," doubtless Mr. Theo- 

 bald is here referring to the Chalcidida^. It would be inter- 

 esting to learn what efforts have been made in this country 

 to ascertain how far " our worst pests seem immune against " 

 Hymenopterous parasites. If the natural parasites have 

 been found and their presence established, then experiments 

 and trials ought to be carried on and the results published, 

 and then one can judge more accurately as to the general 

 question of economic importance of the Coccid parasites. 

 * Rep. South-Eastern Agric. Coll., Wye ; March 1902. 



