PROCEEDINGS OF THE THIRD EXTOMOLOGICAL MEETING 679 



been in Hawaii sufficiently long to have definitely shown such tenden- 

 cies. Being a part of the Tropics, the flora in general and the crops 

 in particular in Hawaii are unlikely to be very dissimilar to those in 

 India. If the fly has not become a pest of other plants during a decade- 

 and a half in Hawaii, it is not more likely to do so in India. Moreover, 

 unlike Scale-insects, which will adapt themselves to almost any plant, 

 the fly is a type of a specialized insect. The tiir Agromyzid which we 

 find in India, has, so far as I know, not been reared from any other 

 plant and it is as unlikely that the Lantana fly wiU turn its attention 

 to any other plant than perhaps L. indica. I think, therefore, that 

 there will be no special danger in introducing it into India, but before 

 doing so, I am of opinion, that we ought to make sure by waiting to the 

 Entomologists in Hawaii and Fiji and New Caledonia, requesting them 

 to let us know their experience in the matter. The behaviour of the 

 fly might also be studied among crops of various kinds, under control 

 in breeding cages, before actual introduction. 



It must of course be kept in mind that our aim in introducing this 

 fly is not to exterminate Lantana but to check the spr-ead of the plant 

 by minimizing the seed production. If this be accomplished, Lantana 

 would settle down into the rank of many a harmless weed whose presence 

 we do not much care about. 



In Mexico and in Hawaii there is a Chalcidid parasite that acts as 

 a check on the increase of the seed-fly. In Fiji it appears that the 

 parasite has been introduced along with the fly and has proved a clog 

 on the usefulness of the insect. It will probably be necessary that the 

 factor of the parasite should, if possible, be eliminated, if the seed-fly 

 is to be introduced. 



Inc[uiries might also be made of the Fiji entomologists if the seed- 

 fly, unaided by the other insect enemies of Lantana in Mexico, is capable 

 of checking the spread of the plant. 



Plant pests. 

 Lantana and Opiintia (Prickly Pear), which are famihar cases of 

 introduced plants spreading injuriously in the countries of introduction,, 

 are by no means the only instances of this sort. I have personally met 

 with numerous examples of garden plants escaping into the surrounding 

 area and trying to elbow out the indigenous vegetation, but u.sually 

 they are mostly annuals and are not sufficiently vigorous. There is 

 however the well-known case of the water hyacinth, and another plant 

 which is at present spreading in alarming numbers and with much greater 

 rapidity than Lantana in the forests of Burma and Assam and around 

 Calcutta. I refer to a plant of the Order Compositse — Eufatmum odora- 



