REPORT OF THE SECRETARY 143 



dom to work if they can. Yet the building is in as excellent shape 

 as when we first put it up. Here again, treated lumber costs perhaps 

 50 percent more, but as it gives freedom from termites, in a few years 

 it pays for itself. 



The above two cases show that with treated timbers you can build a 

 termite-free house even where termites are extremely abundant and 

 active. 



Tests on the island also show that one can build of untreated timbers 

 and have no termite hazard, provided a few simple precautions are 

 taken. The main requirement is to build a good thick concrete floor 

 which will extend out at least to the line of the eaves. The floor must 

 be well made, with no cracks. The secret is to make an inspection at 

 least once a week around this concrete floor, and if termites have 

 built any covered runways, introduce into these runways either pow- 

 dered calomel or finely powdered paris green. In this way the colony 

 is poisoned, and by watching a treated runway, it can easily be deter- 

 miried whether or not the job was well done. It takes so little time 

 and does not need superior knowledge. Of course there must be no 

 leaks, either in the roof or in the plumbing. 



Of course, by the use of properly made termite shields, properly 

 installed, it is possible to keep termites out of buildings. Wliere it is 

 possible to install them, termite shields are cheap protection, but not 

 all buildings lend themselves to the use of shields. Soil poisons also 

 are the answer for some type of buildings, but vigilance is always 

 necessary, and inspection cannot be perfmictory. 



Circular 683, United States Department of Agriculture, "Effective- 

 ness of Wood Preservatives in Preventing Attack by Termites," by 

 Snyder and Zetek, gives a good picture of the extensive termite tests 

 on Barro Colorado Island since 1923. The annual progress reports by 

 Hunt and Snyder in the Annual Keports of the American Wood Pre- 

 servers' Association give details of the more important of these tests. 

 Nearly 4,000 tests are involved, in addition to the Kowal-Dews-John- 

 ston series noted elsewhere in this report. 



LIST OF THE TERMITES OF PANAMA AND THE CANAL ZONE 



In this, the latest list, 57 species are represented, and of these, 45 

 are known from Barro Colorado Island (indicated by the initials 

 BCI). There are 13 new species which will be described in the near 

 future by Dr. Emerson. The Kalotermitidae are those commonly 

 known as the "dry- wood termites." The Rhinotermitidae are the bad 

 actors, Coptotermes niger and Eeterotermes tenuis being especially 

 noted for their destructiveness. Some of the Termitidae are also very 

 destructive. This list is by no means final. We feel that at least 15 

 more species will be discovered. 



