134 HUGH SCOTT. 



found to be dead ; there were four adults on the surface and 34 adults below, and 

 remains of about eight larvae were found. It will be noticed that the adults were 

 six more in number than those placed in the bottle the year before, proving that 

 some of the larvae had succeeded in reaching the adult state ; most of them when 

 put in were fairly big. But the attempt to start a culture breeding in pure cream 

 of tartar failed. It should be mentioned that no moisture was supplied, but neither 

 was it, of course, in the original jar of argol, which was however far larger and 

 contained a very much greater bulk of chemical than the bottle used in this 

 experiment. 



In the original jar of argol the insects were still present in large numbers in 

 April 1921. Series of adults and larvae have been preserved, but I have found 

 only one pupa, though samples of the argol have been looked through on several 

 occasions. This single pupa was found at about the end of March 1921 . Mr. Michael 

 G. L. Perkins, who placed some of the argol in a vessel and kept the beetles present 

 in it under observation, obtained about 30 pupae in July 1920. He has also started 

 cultures of the insect in certain food-stuffs such as oatmeal and raisins, and, so far 

 as his observations have gone, he considers that the generations succeed one another 

 more rapidly in these food-stuffs than in the argol, in which substance the insects 

 appear to be reproducing themselves only at the rate of about one generation a 

 year. He hopes to publish the results of his investigations in the future. 



The larva pupates in a cocoon formed of a feltwork of fine threads, secreted 

 by itself. The cocoon is not lined, and the feltwork is easily pulled apart with 

 needles into a loose tangle of threads. The feltwork appears whitish when the argol 

 powder is shaken away from it. Under a high power (i-inch objective) the threads 

 are quite colourless and transparent. Many full-fed larvae, pupae, and adults have 

 been found in these cocoons by Mr. Perkins and myself. Mr. Perkins sifted the 

 argol, to remove all foreign material from it, before he placed his observation culture 

 of the insects in it, thereby proving that the threads are actually produced by the 

 larvae. He thinks that other feltwork is produced in the burrows, besides that 

 actually used in the construction of the cocoons. 



Trigonogenius globuhtm was originally described from Chile, but is very widely 

 distributed. In M. Pic's Catalogue of Ptinidae (1912, Col. Cat., part 41, p. 9), it 

 is recorded from various parts of North and South America, Tasmania, and England. 

 Most of the known species of the genus are, according to the Catalogue, known from 

 Central or South America, and several of them are not known from, elsewhere, so 

 that region may be their native home. Fowler & Donisthorpe (Col. Brit. Isl., vi, 

 1913, p. 147) state that it has occurred in corn mills and granaries in various industrial 

 centres in England. Champion (Ent. Mo. Mag., 1918, p. 40) records it as having been 

 found under timber and among wood-shavings in London, in company with Ptinus 

 tectus and Niptus hololeucus : and Potter [op. cit. 1919, p. 88) records it from old 

 cotton mills near Manchester, where it was attracted to baits of sugar It is not 

 mentioned in Reitter's " Fauna Germanica : Die Kafer " nor in the addenda at the 

 end of the last volume of that work (Vol. V, 1916), so it had evidently not occurred 

 in Germany up till 1916 within the knowledge of the writers of that book. I have 

 not searched the literature further. Ptinus tectus and Niptus hololeucus, the members 

 of the same family mentioned above, are, like Trigonogenius glohulum, found in 

 various stored products. Ptinus tectus further resembles it in being almost cosmo- 

 politan in range. It may be recalled that larvae and adults of Niptus hololeucus 

 have recently been found in cocoa powder from a south German chocolate factory 

 (Rev. Appl. Ent., A.ix, 1921, p. 66). 



