MONTHLY NOTES ON GRUBS AND OTHER CANE PESTS. 45 
that it would be wise to have more honey-bearing plants on the waste 
ground near grub-infested cane areas, so that the wasps would be 
attracted to these localities and eventually turn their attention to the 
grubs. 
It is well known that the adults of these parasites subsist upon sweet 
secretions, which they secure largely from flowers, when these are to 
be had ; they also feed upon honey-dew, and in breeding them in captivity 
we found that they take any form of liquid sweet that is offered them. 
As far back as 1901 Mr. J. C. Clarke,* of the Hambledon Sugar 
Mill, Cairns, called attention to the importance of planting Congo or 
pigeon pea (Cajanus indicus) around each field, and the growing of the 
Bona Vista bean (Dolichos lablab) as a crop for green manure, so as to 
encourage the multiphecation of parasitic insects which feed on the nectar. 
He observed that the parasitic wasps were abundant at the flowers; and, 
at the time of harvesting the cane, close by in the same field, he discovered 
many of the larve of these parasites in the soil, where they were destroy- 
ing the cane grubs. 
In Mauritius, too, the interesting observation was made that Tiphia 
parallela, which was introduced from Barbados, only reproduced success- 
fully in localities where nectar-bearing flowers were present. In its 
native home this species never was known to visit flowers, for it fed upon 
the honey-dew from aphids. In Mauritius, however, plant lee are so 
well controlled by natural enemies that the wasps were compelled to 
turn their attention to flowers for existence. 
These observations would suggest that our own native parasites of 
the white grubs might be considerably assisted and encouraged if we 
provided them with suitable nectar-bearing flowers in the vicinity of 
the infested cane areas. Naturally, these wasps, in their quest for food, 
are led far into the wild country, and, since they can easily find their 
natural prey, white grubs, there under the grasses, they seldom return 
to the cane areas to oviposit. 
The abundant flowers of the pigeon pea are particularly attractive 
to hymenopterous insects. Furthermore, this plant is of recognised value 
for green manure,t a fact which was demonstrated by the experiments 
of the C.S.R. Company years ago. They found that it was even better 
than the black Mauritius bean, especially for the long fallow during the 
dry months, for its dense foliage prevented the growth of grasses. 
I secured a few seeds from Senator Crawford, who has a fine lot of 
these bushes growing in his yard at Mossman. I shall try some experi- 
ments as to their attractive value for the wasps by planting them along 
the headlands of our infested fields. 
* Agric. Gaz., N.S.W., 1902, pp. 1-6. 
+ See Illustration, «Australian Sugar Journal,” Vol. 1, p. 21. 
