1885.] Forest Trees in South Africa. 23 



Africa, and, although they may be common in the wooded districts, I 

 have only captured 4 specimens of one HylurguSy I believe, near 

 Cape Town, and have never here met with any sign of their presence. 

 No doubt the number of species will be increased by further systematic 

 research. All the Scolytidae attack living trees. 



In the adult state, they notch the bark of trees to extract the juice. 

 The female gets under the bark and hollows out a gallery, making 

 series of notches in the sap-wood as she goes on, in which she deposits 

 an Qgg. The larvae after they are hatched from the Qg^ deposited by 

 the parent insect, begin to gnaw the alburnum or sap-wood and form 

 parallel tunnels proceeding on all sides from the central one, on which 

 the eggs were placed, and form thus a most curious labyrinth. They 

 choose for their resort the trees, the wood of which is of a hard 

 texture. I have noticed traces of the presence of those in the Hard 

 Pear, Olinia capensis, and White Pear, JPterocelastrus rostratus. I am 

 not quite certain that I have also noticed traces in the Iron-wood, 

 Olea capensis. 



Through interruption of the flow of sap, and admission of wet 

 between the bark and wood, decay speedily ensues. 



The damage done by the Scolytidae has caused a great divergence 

 of view among Entomologists and Foresters of great repute. Some, 

 Pat^eburg among them, maintain that they attack the healthy trees ; 

 others, that they select only those trees which, without being exactly 

 in a state of decay, are not in healthy condition. Audouin has gone 

 further, and states that the female Scolyti never lay their eggs but 

 on trees which are in a declining state, and that the healthiest elms 

 on which the Scolyti abound, are constantly brought into this 

 languishing state by the attacks of the males upon the bark, for food, 

 so that, in consequence of the loss of sap from the numerous holes 

 which they gnaw, and the subsequent mischief from the rain pene- 

 trating into them, the trees are soon brought into that unhealthy 

 condition which the instinct of the female requires, to induce her to 

 lay eggs in them." 



It seems however to me that the punctures would detei'mine in 

 healthy trees, a flow of sap which would infallibly drown or agglu- 

 tinate the newly-born larvae ; but on the other hand, although those 

 insects are very small, their number is so great that the extravasation 

 of sap may not be in sufficient quantity to choke the young larvae of 

 all the Scolytidae, although causing the destruction of many. 



LONGICORNIA. 



Some larvae of the insects composing that family, gnaw the bark 

 only without touching the wood ; others excavate very deep in the 

 heart-wood (duramen) and some attack even the medullary substance. 

 If the damage caused by them is less great than that caused by the 

 Bostrychidae and Scolytidae, because they are undoubtedly less 

 numerous ; yet, the large size of most of them compensates for their 

 numerical inferiority. 



Although not always destroying entirely full-grown trees, they 

 nearly always cause the death of young ones. But it is when the 

 trees are feUed and left to season, that they su:ffer most from those 

 insects, and some species abound in timber yards, causing great losses 

 to the owner, and attacking even those logs which are shorn of the 



VOL. rv. L 



