118 
BRITISH APHIDES, 
species, it turned tlie apex of its abdomen towards tbe 
abdomen of the Apbis, and then bent the joints of its 
antennae so as to form a fulcrum, like a knee-joint, 
against part of the wheat ear. A fine but short 
ovipositor was then extruded, and by means of a 
peculiar sawing motion was finally thrust through the 
hardened skin of the Aphis pupa. This motion was 
continued for ten minutes at least, and even after the 
insect was pierced, during which operation probably 
the larva of the Ephedrus was stung and made 
insensible. Finally the Ceraphron introduced its own 
egg, from the grub of which eventually would come 
the destruction of the larva of the parasite, which first 
attacked the larva of 8i]olionophora granaria. This is, 
in fact, a case of the biter bit,’’ and we are furnished 
with an interesting example of one mode whereby the 
balance of life in nature is sustained. The destruction 
of one parasite by another here clearly provides against 
the extirpation of the Aphis in question. The Ephe- 
drus also shows itself a true friend to the farmer ; for 
perhaps twenty or more infested Aphides may be 
counted on a single ear of wheat. 
The pupse of 8, granaria are plentiful at the end of 
July, and the winged females may be taken shortly 
afterwards and until the crops are harvested. 
It cannot be doubted that some species of Aphides 
migrate from plant to plant, and even to different 
natural orders of plants, but I believe no autumn 
migration has been observed of 8. granaria. Bearing 
in mind the observations on dimorphism in Aphis by 
Planchon, Pasteur, and Signoret in France, and of 
Riley, the Professor and State Entomologist of Mis- 
souri, I carefully searched the roots of wheat stubble 
in September so as to discover some possible under- 
ground habit of this species. I could find no trace of 
them around the rootlets, although the aphis had been 
very plentiful on thr ground during the summer. 
White cottony tufts were sparsely but generally 
distributed in the crevices of the soil, from one 
