68 GYPSY AND BROWN-TAIL MOTHS. [Jan. 



sites by study of the biology of the parasites of Lymantria and 

 Euproctis in the country of their origin. 



I believe it will be necessary to study the biology of all parasites 

 that are at all known in parts of Europe and Japan, because I am 

 convinced that the biological knowledge of these insects is the true 

 base of economic entomology; and that in this special ease, where you 

 wish to make use of parasitic insects to fight another insect, it is in- 

 dispensable to have a profound knowledge of their biology. Therefore, 

 I believe that without doubt the biological study of the parasites of the 

 two injurious species of Lepidoptera, in Europe, Japan, and possibly 

 also in the Asiatic continent, ought to be entrusted to a competent per- 

 son. After such study they will be able to determine surely the true rank 

 of the parasites of various species of Hymenoptera, to kill all secondary 

 parasites and to liberate instead only those which are of the first rank, 

 and among these last, if possible, those only that are of special im- 

 portance in combating Lymantria and Euproctis. In the study of the 

 biology there will be brought to light many interesting facts, which 

 will enable those engaged in the work to obtain a sure result, and in 

 the shortest possible time. It seems to me also that it will be necessary 

 to increase the number of entomologists who are occupying themselves 

 with the biology of the parasites in Massachusetts, and that they should 

 occupy a larger laboratory, where the sheds in which they work may 

 be more dispersed, so that the temperature will not be too high, as it 

 happens now in the large shed situated near the laboratory. 



To protect as much as possible the parasites that are now intro- 

 duced, it will be advisable to reserve for breeding places in the central 

 part of the infested territory a certain number of localities some miles 

 apart. Of such localities one should be for the Calosoma sycophanta 

 because, being a predatory insect, it should not be in the same place 

 as the Hymenopterous parasites; and the other localities for the 

 Hymenoptera and Diptera should be reserved as much as possible for 

 the species of parasites of the various orders, so that each species 

 should remain alone for some time to combat in a given locality the 

 gypsy moth and the brown-tail moth. In the localities reserved for 

 the action of the parasites artificial suppressive measures against the 

 two Lepidoptera should not be carried on to extremes, but only such 

 as are necessary to reduce the insects in numbers so that the trees 

 surrounding shall not be defoliated, but so as always to leave a suffi- 

 cient number for the parasites. Such partial artificial methods ought 

 to be directed against the egg when there are plantings of the parasites 

 which attack the larvse and pupas, and against the larv® in turn when 

 the parasites attack the eggs. By such methods I believe the best con- 

 ditions possible for favoring the multiplication of the parasites in the 

 field will be obtained, and the beneficial results from the introduction 

 of the same parasites will be hastened. 



