4 BULLETIN 204, U. S. DEPARTMENT OF AGRICULTURE. 



adjoining tree growth in search of food. Dr. Summers estimates that 

 not less than 5,000 acres were almost completely defoliated in the 

 forests in Hungary where he made his observations. The growth 

 consisted entirely of hardwoods; the oak predominating, and a 

 species of Carpinus, beech, and maple occurring in the order men- 

 tioned. A few elm trees were also present. 



The results of the European investigations carried on during the 

 past few years, aside from furnishing a good supply of parasitic 

 species, has proved beyond question that as far as the forests are 

 concerned the character of the growth is of prime importance from 

 a gipsy-moth point of view. Coniferous forests predominate in Ger- 

 many, and these are not injured by the gipsy moth. The deciduous 

 forests in that country are not large, and the injury is periodical and 

 severe. In Hungary large deciduous forests are present and the 

 infestation is more or less common from year to year. Severe defolia- 

 tion usually continues for about three years before a marked decrease 

 of the moth is observed, and then a few years pass before another 

 outbreak is noticed. This information, with certain data which have 

 been collected in this country for the past few years relative to the 

 increase or decrease of the gipsy moth under New England forest con- 

 ditions, together with a careful study of the feeding habits of the 

 gipsy-moth caterpillar in all its stages on the various species of tree 

 growth, and the beneficial influence which is being felt to a greater 

 extent each year as a result of the increase of the parasites and 

 natural enemies of the moth and the severity of the wilt disease, all 

 point the way to more effective methods of handling the gipsy-moth 

 problem. 



The different phases of the experimental work, as it is being carried 

 on, will be touched upon briefly in order to indicate the changed con- 

 ditions which are being brought about in the infested area in New 

 England. 



PARASITE WORK. 



As has already been stated, the first attempts to introduce the 

 parasites and natural enemies of the gipsy moth and brown-tail moth 

 were begun in 1905. In all more than 30 enemies of these insects, 

 which are present to a greater or less extent in their native homes, 

 have been introduced into New England. More than half of the 

 species have been received in sufficient numbers so that colonies 

 could be liberated under field conditions, and they have had an 

 opportunity to demonstrate their ability to withstand climatic con- 

 ditions and to become established in this country. As should be 

 expected, a large number of the species have failed to survive. A 

 few have been recovered from year to year, showing that while they 

 have the ability to maintain themselves, they have not yet been 

 able to increase to a sufficient extent to become a useful factor in 

 controlling their hosts. A few species have become established and 

 are increasing satisfactorily. In fact, some of them are making suffi- 

 cient headway so that they have already become a very appreciable 



