-SO Fiftieth Report ox the State Museum 



mounds built as an extension to the underground burrow (Pis. X, XI). 

 Only two other instances of their occurrence prior to this have been 

 given by writers, to be noted hereafter, and but one example was known 

 in any collection — in that of the National museum at A\'nshington, de- 

 posited there over twenty-five years ago. 



The distribution of these above-ground chambers and the causes lead- 

 ing the larvae to construct them, can not be satisfactorily explained. 

 Their occurrence under widely different conditions, and the theories 

 advanced to account for their building, renders it desirable that their 

 localities be given so far as known. 



Their Abundant Occurrence in New York. 



To Benjamin Lander, of Nyack, N. Y., belongs the credit of 

 having discovered and studied on South Mountain, near Nyack, 

 by far the largest tract of ground thickly dotted with these 

 chambers that had ever been observed. The total area was esti- 

 mated by him at about sixty acres, with five to twenty-two of 

 the structures to the i^quare foot. Those to which his attention 

 was first drawn, occupied a small tract of woods that had recently been 

 burned over. Subsequent visits extended the area far beyond this tract, 

 and included ten acres of open land which had been wooded in 1877. 

 Other localities of the chambers, varying in their extent, were also found 

 by him at Nyack, Upper Nyack, South Nyack, Grandview, Piermont, and 

 on the top of the Palisades near Alpine. Several of these areas had been 

 burned over. Mr. Lawton, superintendent of schools at Nyack. found the 

 chambers in small numbers on a slight terrace in his yaril, and although 

 hundreds of the insects came up in other portions of the yard, no chambers 

 were built. Quite a number were found at West Point; at New Windsor, 

 Miss Morton observed them in the grass and in the rows between the 

 garden plants. A few, which were about two inches long and nearly 

 horizontal, were reported from Johnsville. They were also seen at Marl- 

 boro in the woods, and probably further search would have revealed 

 others. In the sandy soil of the woods along the river at Pough- 

 keepsie, the ground was thickly covered with them. At Bangall they 

 were found under the leaves in the woods among three times as 

 many uncapped holes : several acres were dotted with four to ten 

 holes to the S(]uare foot. At Athens, in one locality, the soil was not 

 much over two feet in depth where the chambej's occurred, while in 

 another locality covered with bushes, no rock could be found at a reason- 

 able depth. Mr. Brooks of Athens had noticed the chambers in his 

 apple orchard in great numbers when cultivating it. The clay was then 



