BENEFICIAL VERSUS INJURIOUS INSECTS. 
of ascertaining their life history is to make conditions as near natural 
as possible. Cages of various kinds covered with muslin or wire mesh 
are in common use. Some may be flower pots in which the host plants 
are growing, covered with lamp chimneys, wre screens, or © other 
arrangements. Other breeding cages may be of a large size used in the 
open, completely covering full-grown plants. In the study of under- 
ground forms, such as white grubs and wire worms, the cages are usually 
buried in the soil. The environmental conditions must be studied, 
e.g., aphids readily succumb to heat, and the cages may be placed in 
shelters covered wth a canvas screen, or they may be shaded by trees. _ 
Other Australian parasites taken to California by the late Mr. 
Vosler were:—(1) A predaceous moth, Thalpochares cocciphaga, one 
of the most important of our enemies of the Black Scale (Saissetia 
ole). The larva of the moth feeds on all stages of the scale, but seems 
to prefer the eggs. From full-grown larve placed in cold storage 
seventeen moths were reared at the Insectary, and these have since been 
propagated through several generations. They have given great promise 
of being active predators of the Black Scale of Citrus in California. 
(2) Internal parasites, Aphycus lounsburyti and Coccophagus sp.. 
on Black Scale appear to be successful. 
(3) The ege parasite, Scutellista cyanea, a chalcid, was also found 
at work in New South Wales. This was first successfully introduced 
to United States of America from South Afr’ca, in 1901. 
(4) A parasite of a mealy-bug from an ornamental tree in Brisbane 
Botanic Gardens proved to be Paraleptomastix abnormis, the same as 
was brought from Sicily to California some years previously. There 
does not appear to be much doubt that the mealy-bug and its parasite 
were brought to Australia on imported. material from Italy... The 
Citrus mealy-bug, Pseudococcus citri, has been a serious pest in United 
States of America, and parasites have been successfully introduced from 
Sicily, Japan, the Philippines, and Australia. A ladybird, Midas 
 pygmeus, from Victoria, is breed‘ng and feeding readily on citrus 
mealy-bug in Oalifornia, and is considered a good addition. — 
The Australian gum-tree scale, Hriococcus coriaceous, spread with 
marvellous rapidity in New Zealand, right from its introduction, so 
that within five or six years the eucalyptus plantations of Canterbury 
and Otago were seriously infested. In Australia. the scale is not so 
destructive, being held in check chiefly by the ladybird Rhizobwus 
ventralis. In the bush, .R. ventralis is quite common on young eucalypts 
attacked by Black Scale. Consignments of the beetle were taken to 
New Zealand and established within the affected areas. In a few 
years the scale was practically eliminated. It is largely grown in 
California to control the Black Scale, which there is one of the most 
serious pests on citrus and olive trees and many deciduous*trees. Many 
species of parasites of the Black Scale were reared in California from 
material sent from South Africa. At least two primary parasites were 
reared, while many secondary parasites had to be eliminated. Both 
primaries emerge from the young ‘scale before the eggs are laid, and 
hence filled a long-existing gap in the des‘red sequence of parasites. 
They became valuable additions to Scutellista cyanea and Tomocera, 
which attack the scale after the eggs are laid. 
(To be continued.) 
483. 
