REPORT OF CRANBERRY SUBSTATION FOR 1915. 39 



into the spring. If these tests show accurately what actually occurs 

 on the bogs, we seem forced to the conclusion that most, if not all, of the 

 infestation found on a bog in any season immediately following a late 

 holding (until May 20) of the winter flowage comes from the upland that 

 season and does not have its origin on the bog itself. 



In the opinion of the writer the temperature of the water is the principal 

 factor in determining the effect of submergence upon the worms (in 

 cocoons), though this has not yet been definitely proved. 



The season's records show a considerably higher total parasitism for this 

 insect than was found in 1914, but such a difference may not really have 

 existed, as the study of the parasites was less advanced and less thorough 

 last year than this. The records for this season seem fairly accurate, and 

 the high percentages of parasitism found seem surprising. Special atten- 

 tion was given, as last year, to the three principal parasites: viz., the 

 Braconid (Phanerotoma tibialis, ^ which parasitizes the worms), the Ichneu- 

 monid {Pristomeridia agilis,^ also a worm parasite) and the Chalcidid {Tri- 

 chogramma minuta, an egg parasite). The Phanerotoma parasitism was 

 found to range this season from about 27 to 72 per cent, on dry bogs 

 (without winter flowage), and from almost none to about 22 per cent, on 

 bogs that had the winter flowage held late. The Pristomeridia parasitism 

 ranged from about 5 to about 38 per cent, in fruit worms taken from dry 

 bogs, and from none to about 7f per cent, in those from bogs that had the 

 winter flowage held late. Fruit worm eggs showed a range in Tricho- 

 gramma parasitism of from 42 to about 89 per cent, on dry bogs and 

 from about 12 to about 89 per cent, on those with winter flowage. It will 

 be seen that the parasitism, as a whole, ranged, as in previous seasons, 

 considerably higher on dry bogs than on flowed ones. As a result of these 

 investigations, the writer estimates that all the natural insect enemies 

 (including such predacious forms as spiders and ants with the three 

 parasites here mentioned and other lesser ones not discussed) of the 

 fruit worm took care this year of not less than 97 per cent, of the entire 

 infestation on some dry bogs and of close to 90 per cent, on some flowed 



1 There is some doubt about this specific name. Mr. A. B. Gahan, of the Bureau of Ento- 

 mology of the United States Department of Agriculture, regards the species as being new to 

 science. 



2 Specimens of this species were sent to Mr. A. B. Gahan, and he replied concerning them 

 as follows: "Your specimens agree with Pristomeridia agilis Cress., except that they are con- 

 siderably larger. I can find no character to distinguish them from that species other than size. 

 They also appear to agree with the type of P. euryplychice Ashm. In size your specimens are 

 more like the latter. I am unable to say whether agilis and euryptychia: are the same species 

 or not. So far as I can see they are alike structurally, and it may require a knowledge of their 

 biologies to determine whether they are different. Euryptychiw was supposedly reared from 

 a lepidopterous gall maker on Solidago, and it would seem a little strange to find the same species 

 parasitizing the fruit worm, although not impossible. The parasitism of agilis is apparently 

 unknown. You had perhaps best use the name agilis for your species for the preser.t." 



In a second letter, written after he had examined the smallest specimens of the species which 

 the writer could find, he added the following information: "Your specimens agree nicely with the 

 type of euryptychim in size as well as structure, but your smallest specimen is still much larger 

 than the type of agilis. I am strongly inclined to think that the two species are synonymous, 

 but would like to have specimens showing better the gradation in size from one to the other before 

 stating that they are the same." 



