MEMO IHS OF THE QUEENSLAND MUSEUM. 
96 
SOME FIELD NOTES ON QUEENSLAND 
INSECTS. 
By Henry Hacker, F.E.S. 
Order HYMENOPTEEA, Family SPHECIDJ3. 
Sphex (Isodonfcia) nigellus, Smith.* — The recorded habits of members of 
the genus Sphex show much similarity. They have generally been found to make 
underground burrows terminating in a chamber, in which they store different 
kinds of insects as food for their young. This season I had an opportunity of 
observing something of the economy of Sphex nigellus, and can record a remark- 
able difference from the usual habits of wasps belonging to the genus. 
This species utilises for nests old beetle burrows in posts and dead trees, 
which it closes by stopping tightly with grass-seeds. On several occasions while 
examining posts full of old disused tunnels, wdiieh had evidently been made 
by some beetle, I had noticed that a number of the holes had been recently used 
by some other insect which had stopped them up with grass-seeds, leaving tufts 
protruding about a quarter of an inch. I did not connect this fact with the 
wasp until some time later, when Professor Skertclily brought to the Museum 
part of a large log similarly affected. This block wajs cut in two, one piece 
being left intact with the intention of breeding out the insects. The other piece 
was chopped up, thus exposing the tunnels. The section of a tunnel when 
exposed gave one a good insight into the methods of this wasp. In nearly every 
instance the tunnels were found to curve downwards from the entrance for 
about half their length, the rest of the distance being nearly horizontal; the 
average length was from three to four inches. The egg was evidently laid at 
the extreme end of the tunnel, a space large enough for the metamorphoses of 
the insect being left there. In this space also was stored the provisions 
(consisting of spiders) for the larva. The remainder of the tunnel was packed 
with grass-seeds, which were loosely packed at first, but got tighter as the 
entrance of the tunnel was reached. The grass-seed used by this wasp for the 
purpose of plugging the entrance to the tunnel is Andropogon pertusus, Willd. 
(Queensland Flora, vol. 6, p. 1863), which it skilfully manages to place with 
all the axillary ends directed inward, leaving the plumose ends protruding like 
a brush. Taking into consideration the shape of the seeds, and the fact that 
the wasp had to push them in from the outside, this was the only method by 
which it could plug the hole tightly. This arrangement made the tunnel quite 
* The insects mentioned in this paper are exhibited in the Insect Court at the Queensland 
Museum. 
