SUPPLEMENT TO PSYCHE. 



clouds, and I seized the opportunity to 

 get up in the hills among the giant 

 cactus. I found a mountain side 

 covered with cacti of the utmost variety 

 with the Giant Cereus by thousands. 

 There were, however, few of the latter 

 with large cavities, and it was only after 

 prolonged search that I found one 

 immense fellow the lower three feet of 

 which was entirely dead, even the heart 

 and all around, but this part was quite 

 dry, and the skin hung in patches upon 

 the wooden axis. Only a small corner 

 was wet and putrescent, and tliis 

 presented in part the usual fauna but 

 nothing new. P/iysetoporiis g'rosszthis 

 was especially abundant. There was 

 one specimen only of Xaiitliopygus 

 cacli\ and of course I secured that. It 

 is strange that there were no Rhyncho- 

 phora in .this stem, and the upper part 

 of the latter with three huge branches 

 was quite sound and still alive. I saw 

 two other plants of the giant cactus still 

 standing although quite dead and dry. 

 I sifted the debris of one of these in the 

 hope of finding Pselaphids but there 

 was nothing but a few Poduras and 

 Forficulas. There must be a fatal rot, 

 which, like a tuberculosis, entering at 

 some woodpecker hole lays low these 

 giants. Evidently they take years in 

 dying. There is a large yellow Polistes 

 {P. Jlavus Cr.) which hangs its comb 

 in some of these cavities, and I find not 

 seldom the hibernating wasps. Besides 

 the Nariiia femorata mentioned before, 

 several other large Heteroptera (Sinea 

 raptoria, Diplodus Inridiis, Dendro- 

 corus conianiinaiiis, Brochyviena ob- 



sciira) are found hibernating in these 

 cavities and some of these are probably 

 feeding on cacti later in the season. I 

 also found a colony of termites ( Te.rnies 

 flavipes ?) burrowing in the hard crust 

 of the cactus in a woodpecker hole. 



Tucson, Ar., April 22, 1S97. 



The entire mesa at the foot of the 

 Sta. Catalina Mountains near Sabina 

 canon, about iS miles northeast of 

 Tucson, is covered for miles and miles 

 with immense giant cactus, in one 

 unbroken army, as thick as mullein 

 stalks in an eastern cattle pasture. 

 Out of these thousands of cacti I did 

 not discover a single plant that was 

 diseased or rotting, and only near the 

 camp a few of the trunks ha'd been 

 overturned. This seems to me to 

 indicate great longevity in the Cereus 

 since among so vast an assemblage 

 many dead and dying plants would be 

 found if their period of life was not a 

 long one. Also I think it gives weighty 

 evidence as to the correctness of my 

 siu'mise that disease and rot in this plant 

 is started chiefly by the disorganization 

 produced in the woodpecker holes by 

 rain water acting on the dung of 

 animals that lodge in these holes. In 

 this vast forest of stalwart plants, wood- 

 pecker holes are of course comparatively 

 rare since the plants outnumber tiie 

 woodpeckers of this region very many 

 times. Around Tucson where the cacti 

 are far less abundant on the hill sides, a 

 great many of the trunks are pierced 

 with holes, and a comparatively large 

 proportion die of this black rot, which 



