1903.] E. P. Stebbing — Discovery of Thanasimus sp. yrox. nigiicollis. 107 



Life History. It is possible that the Thanasimus is to be found on the 

 wing more or less continuously from spring to the end of autumn in the lo- 

 calities which it affects. The eggs have not yet been discovered, but they 

 are probably laid on the bark of the trees near or in the entrance holes of the 

 bark beetles, and the young larvae, or hatching out, make their way down 

 these tunnels into the egg galleries in the bast and sap wood and from 

 thence into the larval galleries. My observations up to the present have 

 shown that larva? of all sizes are generally to be found in these situa- 

 tions between May and October. The length of time spent in the larval 

 stage is at present unknown, but it is unlikely to be more than'a month 

 in the case of the summer generations. On becoming full grown the 

 grubs go into the thick outer bark of the tree to pupate. This is to 

 facilitate the beetle when mature leaving the tree. The adult never 

 enters the tree. It is a brightly. coloured, very active insect, running 

 and flying well even in hot sunshine, and it spends its life flying round 

 or running about on the bark of the trees. Its food consisting of bark 

 and wood boring Scolytidse, it searches for these on the bark, since it is 

 much too bulky to enter their tunnels, and seizes them whilst they are 

 engaged in either boring into or tunneling their way out of the tree. 

 In the case of the Scolytus major and minor beetles, upon which it was 

 preying when discovered, it would appear that they form its food for 

 some weeks or months during the year, since they remain alive after egg- 

 laying and until the larvse are full grown. The mother beetles spend 

 their time walking up or down the egg-gallery, or going up the entrance 

 hole to the outside and the Thanasimus watches at the mouth of these 

 holes and seizes and devours the beetles when they appear at the mouth 

 of the tunnel. They only feed upon living beetles, and will not touch 

 dead ones, and they catch their prey by sight only and not by scent: 

 unless the bark beetle is right in front of them they will pass it by 

 unnoticed. I was able to definitely ascertain this point by a number 

 of experiments. Beetles kept for twenty-four hours without food pass- 

 ed close to their prey without, noticing it although they were in a 

 ravenous condition. It would appear that they only see directly in 

 front, and this is borne out by the position of the eyes which are placed 

 rather forwardly upon the head. When, however, the scolytid comes 

 within their range of vision they pounce upon it, just as a tiger does, with 

 one rush and if out of its hole the bark beetle has not the remotest 

 chance of escape. I have not been able as yet to observe whether they 

 ever take their prey upon the wing. The clerid seizes the bark-borer 

 with its anterior legs and mandibles, picks it up off the ground, turns 

 it round so as have the ventral surface facing it with the head upper- 

 most, sits well back on its hind legs and commences to feed upon its 



