1 Fes., 1902.] QUEENSLAND AGRICULTURAL JOURNAL. 137 
it does so deeply into the living tissues of the latter, remains stationary, fixed in 
this position, until fully developed and ready to undergo metamorphosis. 
The position, with respect to the grub in which it is fixed, as well as the fact that 
the head and body are notin a single straight line, aid it, moreover, in retaining 
its hold, notwithstanding the movements of its victim. The larval Diels mean- 
while feeds on the soft tissue as well as on the liquid contents of the grub’s body, 
and so increases in size as it does so. This increase takes place so rapidly that 
it may attain its maximum development within a fortnight or less. Its appetite, 
moreover, is voracious; for, notwithstanding the fact that the beetle-grub 
continues for a while to feed, its body gradually becomes more or less flaccid and 
collapses. That the existence of its victim may persist for a sufficient length 
of time, the Déelis larva is careful, whilst indulging its carnivorous appetite, to 
avoid injuring any organ on the intactness of which this persistence of vitality is 
dependent. Death, however, ensues before the grub can transform to its pupal 
stage. Ultimately the host-insect is reduced to an empty skin, in which all the 
hard parts can be recognised as remaining uninjured. 
The Dielis larva has meanwhile freed its fat and sleek body, and 
soon commences to fabricate a silk-covered elongate oval cocoon that 
occupies in the soil the space previously filled by the beetle-grub. ‘These 
cocoons vary in size from 380 mm. (13 inches) long by 15 mm. (3 
inch) broad, to 24 mm. by 12 mm. These are the dimensions of those 
that are to give rise to female “wasps.” Those from which male insects 
will emerge also vary in size, but are usually 21 mm (% inches) by 9 mm. 
(4 inch). The silky investment, that is at first of a pale greyish-yellow colour, 
becomes ultimately a rich glossy tan-brown. It is in two readily separable 
layers, one of which is in contact with the soil, and the other with the dense 
black elongate-oval chrysalis proper that has been formed from the altered 
epidermis of the larva. The cocoon itself manifests considerable strength and 
toughness, and so cannot readily be torn open. 
On opening one of the above-mentioned cocoons, the parasite will be 
discovered in various stages of growth, according to the time that may have 
elapsed since it has been fabricated ; but when this has been of sufficient 
duration the perfect insect will be recognised in the nymphal condition, with 
its legs folded up, and these and its wings and antenne and other organs 
enveloped in separate sheaths, that in the case of the last-mentioned organs 
resent a pad-like appearance. The mouth organs also are very prominent 
nee in the somnolent inactive nymph, especially so in the case of the 
female insect, in which, during the next stage arrived at in the course of 
insect transformation, they will perform as digging instruments so important a 
role. 
For a time the cocoons lie side by side with the remains of the grub that 
has been destroyed, that now become brown and fragmentary. 
The mature Delis, either male or female, however, in due course emerges, 
having first freed itself from its nymphal investments, and then cut the cocoon 
open by a clean circular incision that separates one extremity. 
The parasite now tunnels its way to the surface, availing itself, it may be, 
in doing so, of the partly-filled channel formed by the beetle grub in descending 
downwards in the soil—a movement that is effected by the latter when full fed. 
A living female Dzelis, with its wings frayed and broken, was on one 
occasion dug up in the field whilst still several inches beneath the surface. In 
its case it was evidently returning to the daylight and free air after having in 
darkness performed the laborious work involved in attaining its victim, and 
after haying attached its ege thereto. 
The cocoon of the Dielis has been encountered at a depth of 83 feet from 
the surface. The larva that fabricated it may, however, have been borne 
downwards by the beetle-grub whilst still attached to the latter; for at certain 
periods in its early life it can only be separated therefrom with the exercise of 
considerable force. But although the parent parasite may not have been 
compelled to tunnel downwards to this extent in order to seek food for its 
