BIOTIC ASSOCIATIONS OF COCKROACHES — ROTH & WILLIS 349 



deck officer confirmed the number of cockroaches. The petty officer 

 signs the seaman's name, name of division, rank, and date to be 

 on shore leave in the log book for cockroach shore leaves. The 

 petty officer brings the log book again to the deck officer to get his 

 approval and then goes to the commander for the final approval. 

 In the Navy, they have another special shore leave for rats. In 

 this system, a seaman gets one day shore leave for one rat. The 

 formalities for the latter are the same as for the former, and there 

 is a log book for the rat shore leave in the petty officer's quarters. 

 The author took advantage of these systems frequently. 



SoNAN (1924) 



Little is known of the effects of predatism and parasitism on 

 natural populations of cockroaches. Many statements in the literature 

 are very general; yet there are a few data on egg parasites (e.g., 

 Tetrastichus hagenotvii) which suggest that, in the absence of para- 

 sites, populations of domestic cockroaches might be much larger than 

 they are in certain areas. We have summarized the literature on 

 natural control and also that on the use by man of predators and para- 

 sites in the biological control of cockroaches. However, because of the 

 paucity of information, we have been unable to evaluate the effective- 

 ness of biological control in reducing the numbers of pest cockroaches. 

 This is an area that might reward further investigation. 



INVERTEBRATES 



Scorpions. — In Puerto Rico, cockroaches are probably the principal 

 food of the scorpions which live in old houses, on tree trunks, etc. 

 (Sein, 1923). The staple diet of scorpions in Arizona is the small 

 cockroach commonly known as the water bug (Stahnke, 1949) ; in 

 the part of Arizona where he resides, Stahnke (personal communica- 

 tion, 1953) says that the "water-bug" is most generally Supella 

 supellectilium although Blattella germanica is also found, but less 

 abundantly. 



Spiders. — Jefferys (1760) mentioned a large spider which was pro- 

 tected in the Antilles and especially on Guadeloupe because it hunted 

 down and fed on cockroaches ; the spider was reputed to be common 

 in every house. Sir Hans Sloane (1725, in Cowan, 1865) reported 

 that residents of Jamaica kept spiders in their houses to destroy cock- 

 roaches. Takahashi (1924) reported that, in the Taihoku area of 

 Formosa, human habitations contained large numbers of spiders which 

 caught and ate cockroaches. Smith {in Marlatt, 191 5) reported that 

 Brazilians encourage large house spiders because they tend to rid the 

 house of "other insect pests." In British Guiana tarantulas were kept 

 in a bungalow to control Periplaneta and Pycnoscelus (Beebe, 1925a). 



