4 DESTRUCTIVE INSECTS OF VICTORIA: 



than those of the Black Aphis which have come under my 

 notice, and, being green, are not so conspicuous when on 

 the tree. 



On our Plate (Fig. 1) is shown a portion of the branch 

 of a tree, there not being sufficient room for a figure 

 illustrating the insects on the roots. This, however, is 

 shown on the large charts which, by permission of the 

 Department, I have had prepared for lecturing purposes, 

 and which may be seen by any one interested at the office 

 of the Government Entomologist, Exhibition, Melbourne. 



With regard to the rostrum of an Aphis, which organ 

 plays such an important part in the economy of the insect, 

 Buckton remarks that aphides are wholly suctorial in 

 their habits, and depend entirely upon the sap of different 

 plants and trees for nourishment. As the sources of their 

 food vary, so the rostrum undergoes modification to meet 

 special requirements. Whilst some genera are furnished 

 with exceedingly short rostra, others show the organs 

 produced to an extraordinary length. The most marked 

 example of this peculiarity may be noticed in Stomaphis 

 quercus, which seeks its sustenance in the alburnum or 

 inner bark of the dense trunk of the oak tree. Here the 

 rostrum is nearly twice the length of the insect, and the 

 setae or hairs are very much longer. By these piercers the 

 insect burrows under the hard masses of the cortex, and 

 produces, by their irritating and inflammatory action, a 

 plentiful flow of sap. The juices are drawn into the 

 mouth by a sort of alternating or pumping motion, 

 analogous to that seen in the honey bee. It may be 

 interesting to know that, according to Buckton, in by 

 far the greater number of cases the males and viviparous 

 females of aphides are provided with four wings, as shown 

 in Fig. 2, a female, of course highly magnified, the little 

 cross beneath the figure being about the natural size of 

 the insect with wings expanded, by which they transport 

 themselves into other localities, either in search of fresh 

 food or for the purpose of founding new colonies, and it 

 is the nervation (nerves), or venation (veins), which ento- 

 mologists find of such great value in determining or 



