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* 8 lines and 1 inch. These insects during overcast weather may be seen to Wa 
140 QUEENSLAND AGRICULTURAL JOURNAL. [1 Hup., 1900) 
This experience results from the operations of so-called natural enemies! 
which category may be included not only predatory birds and other insects 
find sustenance in preying upon their bodies, but parasitic forms of life to WM) 
the bodies of these caterpillars serve in the general capacity of host, provit 
at the same time not only aliment but dwelling-place also. As an instance! 
this, a plague of caterpillars caused some consternation by reason of its ravag 
in the district immediately to the south of Brisbane during March, 1895. ; 
immediate descendants of these marauders still exist, score of generalitl 
having succeeded one another since then; and yet we have Jearnt of no fur ‘| 
trouble from caterpillars in the districts alluded to. But that this would be® 
was predicted by the writer at the time, after having remarked the extent! 
which parasitic insect had victimised these grubs concerned in the ravag) 
complained of. And, in addition to the insect parasites, there are also ¢e fi 
fungi (Entomophthorew) and bacteria that produce general and fatal disease? 
the course, too, of their parasitic life in the tissues of these insects. gil 
In the case of the visitations of caterpillars in September-October, 15” 
that have suggested the preparation of this article, similar checks on incre 
were also operative, and no doubt in consequence similar beneficial results | 
those aboye alluded to will follow in most of the localities that have suff 
In the present instance parasitic insects were principally concerned, ® 
amongst these the following ‘are worthy of being especially mentioned :— _ 
A. Ivsror Parastres. 4 
Theronia rufipes, sp.nov. TheRedIchneumon. (Plate CLXXTV., Fig. 2) 
This is a deep-red and glossy insect, having smoke-coloured wings that ap ial 
steel-blue in certain lights, and the anterior two-thirds of its hind body b! ‘ 
and conspicuously spotted with a row of large white spots along each 5) 
Very large female examples may be 11 lines in length, and have a wing §P It 
of nearly 13 inches, but as a rule in this sex their measurements are respectlti 
on and explore in plants that are frequented by caterpillars ; but it is during" 
prevalence of hot sunshine that they occur in greater numbers, though the! 
extreme activity then often leads to their being overlooked. At this 4) 
however, they may be remarked, passing rapidly to and fro just above ”) 
surface of the grass or cereal crop, ever and anon suddenly alighting i 
creeping amongst the herbage. ven at nightfall they are still at their p&, 
remaining three or four together stationary on the grass stems. On discovell™™ 
a caterpillar they soon settle upon it after exploring it from all sides with ™, 
feelers, and notwithstanding the violent contortions into which it throw’, 
head and body. Then they probe it deeply with their black needle", 
ovipositor (composed of three separable parts and measuring 4-incl 
length), and so place within its body one or more of their eggs. It is proba” 
also that at the same time they either disperse in the air or inject into the oe 
of their victim a fluid analogous to formic acid that they secrete, and that Py 
serve the purpose either of an anesthetic or preservative. One, at least, EC iit 
A 
as 
= 
2 oS eS 
eggs of the ichneumon thus inserted hatches into a maggot that feeds witht 
caterpillar, and continues to develop as the growth of the latter is still 
tinued; but at the same time it ayoids touching organs the injury of W 
would result in speedy death. Rt, 
Meanwhile, the caterpillar enters the ground, and, in the majority 5 
instances, transforms to a chrysalis, Further transformation on its pal! 
however, restrained, for, instead of a moth emerging from the ground, # i 
issues the red-bodied ichneumon fly, which digs its way to the surface thr” 
a small circular hole, that is sufficiently large to be readily perceived. ifs 
In the case of some chrysalises of grass-feeding caterpillars (Spodop 
mauritia) obtained during April, 1895, in the Tingalpa district, through *y 
instrumentality of Mr. A. Grieve, it was remarked that, with the exceptio? (t 
an exceedingly small percentage, all gave birth to these parasites in let” 
moths. | 
er 
