52 IMPORTED PARASITES. 



Earlier in this paper an attempt was made to point out the 

 necessity of establishing a sufficient number of parasites to form 

 a natural sequence, which would attack each stage of the moth, 

 from egg to pupa. Every parasite necessary to make an effective 

 sequence is represented in the list given, but there are several, 

 including at least one of considerable importance {Blepharipa 

 scutellata), which may not become effective before 1916. Since 

 the chain is no stronger than its weakest link, the sequence of 

 parasites will not become fully effective until each necessary 

 component of the sequence has reached the necessary abundance. 

 It will be 1916 before the complete control of the gypsy moth in 

 ISTew England can reasonably be expected, and, unless the writer 

 is mistaken, this control, when it is effected, will be general over 

 all of the infested area. 



THE WORK IN I9J0. 



The year 1910 will be crucial in one respect, since it will give 

 ample opportunity to prove or disprove a number of the premises 

 which have been used as a basis for the above calculation. It 

 ought to be possible to follow the progress of several parasites 

 very exactly, and their progress must be proportionate to the dis- 

 tance which they must travel if they are to become effective in 

 their respective roles by the time set. Should the actual develop- 

 ments of this season fall short of what is considered to be a 

 necessary amount' of progress, the disappointment of those in 

 charge of the work will be very great. 



It is hoped that Monodontomerus will increase at about the 

 same rate which has prevailed in the past, but a slight falling off 

 is rather expected. In like manner increase in the numbers of 

 and in the territory covered by Calosoma ought to be commen- 

 surate with the progress of this species during the past year. 

 Compsilura ought to be recovered with ease, and it should be 

 possible to determine more accurately its rate of increase and of 

 dispersion. Tachina ought to be recovered for the first time, and 

 Tricholyga may or may not show decided increase, owing to the 

 doubt which exists concerning its early history in America. It 

 is hardly expected that Glyptapanteles will be found at all. If it 

 were, the circumstance would be more encouraging than any- 

 thing which has happened: first, because it would allay the 



