1924 ENTOMOLOGICAL SOCIETY 35 



The larvae of native Calosomas do not climb well and secure practically all their 

 food on the ground. This habit limits their ability to increase rapidly and ' 

 renders them ineffective as an enemy of the gipsy moth. 



The females of Compsilura concinnata puncture the integument of the cater- 

 pillars and deposit their larvae in the body cavity. This Tachinid attacks up- 

 wards of 100 different species of native larvae. It should be no more effective 

 as an enemy of the gipsy moth than some of our native species such as Tachina 

 mella, except for the fact that the latter deposits eggs on the caterpillars, and 

 these usually are cast off with the molted skins before the maggots hatch and 

 attack the host. 



Anastatus bifasciatus attacks the eggs of the gipsy moth and the females 

 may frequently be found busily engaged in ovipositing as the eggs are being laid 

 by the gipsy moth female. 



In fact, all of the species that have become established are fitted by special 

 adaptation or habit to prey upon the gipsy moth as their principal host. 



What then has been the effect of the introduction of natural enemies on the 

 gipsy-moth problem? 



It is true that the area known to be infested has increased rather rapidly 

 during the last few years. This is due to a considerable extent to particularly 

 favourable seasons for dispersion of the small larvae of the insect by windspread. 

 Shortage of men and low purchasing power of funds during and since the World 

 War have also rendered the problem of prevention of spread of the insect un- 

 usually difficult. 



In the area that has been longest infested there has been a heavy reduction 

 of the number of favoured food plants, due to their injury or death caused by 

 the insect, or by cutting operations carried on by owners. This has not been 

 sufficient of itself to bring about control. There has been during the past few 

 years a gradual increase in the numbers and effectiveness of most of the well- 

 established introduced natural enemies and during the past season the records 

 show a greater percentage of benefit than at any time heretofore. This state- 

 ment does not apply to most of the territory that has become infested in the last 

 ten or fifteen years, although the different parasites are being colonized as rapidly 

 as possible in the lightly infested region. 



These facts indicate that natural enemies are of great value, and show that 

 the work that has been done thus far has been extremely beneficial. The 

 question naturally arises as to what the future results will be. While it is pos- 

 sible to theorize along this line, the problem is so complicated that predictions are 

 almost pure guesswork. We know what has been done in the past. We hope 

 for even better results in the future, but we must never lose sight of the fact 

 that in spite of the natural enemies the gipsy moth has in its native home, it i§ 

 a pest of prime importance. 



Heavy defoliations occur in Europe periodically. The best information that 

 has been secured indicate that they come at five to eight-year intervals. The 

 conditions under which the gipsy moth increases to a point where it causes 

 extensive defoliation in Europe have not been studied as thoroughly as the im- 

 portance of this problem demands. A start has been made along this line during 

 the last two years and it is hoped that sufficient data may be secured in the 

 future so that the value of the different factors favouring increase or decrease 

 may be more accurately measured. With this knowledge available, it may be 

 possible to come to a more accurate conclusion as to the ultimate status of the 

 gipsy moth in America after its natural enemies have been introduced and reach 

 their maximum of efficiency. It is possible to speculate and theorize indefinitely 



