DYING OF YOITNG PINES IN CIRCLES ABOI^T ANTHILLS 767 



Hill No. I contained black ants 6 to 7 mm. long. From specimens 

 seen at the Experiment Station collection at New Haven this appears 

 to be Formica fusca var. subsericea Say. The eight immediately^^ sur- 

 rounding trees did not show the disease (cp. above), were not dying, 

 and there were no ants nor aphids upon them. 



Anthill No. 2 was the center of a circle of dead trees and contained 

 ants 4 to 7 mm. long and with head and thorax red and abdomen 

 "black.^- This is probably, judging from specimens at New Haven, F. 

 exsectoides Forel. Six trees in the area were leafless and two had red 

 leaves.^^ All of these showed the diseased areas (p. 5, fig. i) and also 

 the borings of the Scolytid beetle (fig. 4). Not far from here were 

 three adjacent trees 10 feet high, showing the disease and the Scolytid 

 work. Of these, two were red-leaved and one sorrel-leaved." Of the 

 living trees surrounding the anthill eight showed the disease and ant- 

 gnawing; five the disease, but no gnawing, and eight neither disease 

 nor gnawing. Of these twenty-one, none showed aphid infestation. 



Anthill No. 3 contained the black ants of hill i {F. fusca var. sub- 

 sericea). The surrounding trees were not dying. On this hill the 

 black ants were observed fighting with the red-and-black ants {F. ex- 

 sectoides) . 



Hill No. 4 was in a patch of sweet fern (Myrica asplenifolia L.) 

 and contained red-and-black ants. The surrounding trees, 18 inches 

 "high, were not dying nor insect-infested. 



Hill No. 5 contained the red-and-black ants. Within a radius of ten 

 feet there were two living pines (two feet high) and none dead. 



Hill No. 6 had red-and-black ants. Four adjacent pines were dead 

 (with red leaves) and there was one blank where a tree had been. The 

 "bark of the dead trees showed signs of the disease. Three adjacent 

 living trees were apparently fungus-infested, the bark at the base being 

 sunken and reddened. Seven living trees near by did not show this. 

 These trees were i to 2 inches in diameter at the base and 7 to 10 feet 

 high. One living tree (one-half inch by y/2 feet, with a double stem) 

 showed the reddened and sunken bark at the base and also gnawing. 

 No ant-aphid infestation was seen on adjacent living trees.^^ 



" Obviously and of necessity "immediately," without exact measurements, must 

 Tje a somewhat arbitrary term. 



" A third type of ant, 5 to 9 mm. long, and with black head and abdomen and 

 red thorax, was observed associated with aphids on trees in low ground, but not 

 in any of the hills studied. This seems to be Camponotus herculeanus L. or a 

 subspecies or variety. 



"These trees are loose in the ground (presumably because of shrinkage), and 

 sometimes ants are rather abundant in the surrounding holes. 



"This sorrel did not have stunted leaves. Cp. p. 8. 



"This was observed on a day with brisk to high wind and there were few 

 insects of any species on the trees. 



