BENEFICIAL INSECTS. 399 



to the practical man that the effect of these holes is to let moisture into 

 the body of the root, and so hasten its decay. Thus the more rapid 

 destruction of the roots accruing from the insect may well be con- 

 sidered as an advantage. 



The insect doing the work referred to is a beetle termed Asemum 

 striatum. The larva is about an inch in length, of a whitish colour, 

 broad at the thoracic portion, and tapering very much in the abdom- 

 inal segments. 



The beetle is of an oblong shape, a dull-black colour, and deeply 

 sculptured. The legs are brownish-black, with deep-black tarsi. 



With, reference to the third division of our subject, it may be noted 

 that it can be divided into sub-divisions, as it were viz., insects 

 which prey directly on other insects, and those which are parasitic, or 

 in many cases indirectly kill other insects. 



As regards those which feed directly on injurious insects, perhaps 

 the best example is the Coccinellidae or " lady-bird " beetles. There 

 are several species of them, and they live on insects, more especially 

 Aphides. They feed on these insects both in the larval and beetle 

 stages. Some species pupate on the leaves of trees, and to a beginner 

 in forest entomology the rolled-up pupa is a somewhat puzzling object. 

 These beetles should be carefully studied in every detail, for not only 

 are they very good friends, but the males often differ so much from the 

 females that they may at first be mistaken for distinct species. 



Many of the Colonial writers give very interesting accounts of the 

 great advantages of introducing a species of lady-bird or Vedalia 

 (Novius cardinalis), the notorious Australian bug destroyer. The 

 bug referred to has been kept in check in many parts of the world by 

 the Yedalia. So that a very good hint is given to encourage lady- 

 bird beetles. 



The field of beneficial beetles in forest entomology is rather an 

 unworked one, and Mr R. S. Bagnall has recently demonstrated this 

 by showing that the beetle JEpurcea angusiala is a parasite on the 

 genus Trypodendron, and this obviously suggests that the parasites of 

 the Scolytidae are entirely an unworked field. 



There are many other species of beetles which might be well con- 

 sidered as beneficial, as, for example, many of the ground-beetles, 

 which live on the larva? of various insects, or other creatures, which 

 in turn feed on the roots of young trees in the nursery. 



The larva? of some species of Diptera are very beneficial in 



