90 GUIDE TO THE AUSTRALIAN MUSEUM. 



is sometimes very al)undant. The Hydrometridce are found upon 

 the surface of pools and fresh water streams. The genus Halohates 

 is marine, being found on the surface of the ocean, frequently at 

 great distances from land. The Uomoptera comprise insects of 

 very diverse forms. The Cicadidce (in Australia erroneously called 

 locusts), ho{)pers, cuckoo-spit insects, the Aphides, and the 

 Coccidida, or scale-insects, are all well-known types belonging to 

 this order. They all live on the juices of plants, some of them 

 causing very considerable injuries, as in the case of the much 

 dreaded vine pest, Phylloxera vastatrix, PI., an insect belonging to 

 the family Aphididce* Besides a large number of Coccididae of the 

 ordinary form, many of which are only too well known to fruit- 

 growers and gardeners, we have a curious group of gall-making 

 species {BrachyscelincB) which are found, sometimes in great 

 abundance, on various Eucalypti. 



Orthoptera (Grasshoppers, Locusts, Crickets, Cockroaches, 

 <fcc.) have the mouth-parts free and formed for biting. The fore- 

 Nvings usually protect the hind-wings, which are net- veined. The 

 transformations are incomplete. This order contains the Oryllidce, 

 or crickets, which are well represented ; of this group we have a 

 gigantic species, Anatostoma australasice, in which the jaws of the 

 males are enormously developed. The Acridiidce, or true locusts, 

 are numerous ; the well-known migratory species, Oedipoda migra- 

 toria, is occasionally found. The MantididcE, the Fhasmidce, or 

 walking-stick insects, and the Blattidce, or cockroaches, all con- 

 spicuous types, are largely represented. The species of the tribe 

 Euplexopfera, or earwigs, are also fairly numerous. 



Thysanura include those destructive insects the Lepismm, or 

 *' Silver-tish," and a great number of obscure forms. 



* On a side-table is a case containing a series of preparations of Phylloxera, 

 illusti-ating the hfe-history of the insect. Most of the specimens are 

 mounted on slides for the microscope, and can only be examined by special 

 application. 



