678 The American Naturalist. [Angust, 
of the volume (189 pages) is devoted to the Chinch Bug—the arch- 
enemy of Illinois agriculture, a voluminous record being made of the 
experiments with contagious diseases carried on by the entomologist 
and his assistants. There is also an article on the White Ant in Mli- 
nois, and in an appendix of 65 pages Mr. W. G. Johnson, assistant 
entomologist, gives an excellent discussion of the Mediterranean Flour 
Moth. 
Flies Riding on Beetle’s Back.—Rev. A. E. Eaton, the well- 
known British entomologist, writing from Bône, Algeria, sends this 
interesting note to the Entomologist’s Monthly Magazine: “Across the 
mouth of the Seybouse, on sandy pasture land bordering the seashore, 
big coprophagous beetles are common, sheltering in large holes in the 
soil when at rest, and running about on business. A small species of 
Borborine may often be seen riding on their backs, chiefly on the pro- 
notum, and about the bases of the elytra—sometimes half a dozen 
females on one beetle. The beetles occasionally throw themselves on 
their backs to try and get rid of them by rolling; but the flies elude 
all their efforts to dislodge them, dodging out of harm’s way into the 
joinings of the thorax and out again, and darting from back to breast 
and back again, in a way that drives the beetle nearly mad. In vain 
she scrapes over them with her legs; in vain does she roll over or 
delve down amongst the roots of the herbage; the flies are as active as 
monkeys, and there is no shaking them off. It is difficult to get them 
off into the killing bottle; nothing persuades them to fly; and they 
would very much rather stick to the beetle than be driven off it down 
into the tube.” 
Proteid Digesting Saliva in Insect Larve.—Dr. Wilibald 
Nagel describes? the method of feeding in larvæ of Dytiscus. In these 
larvee the mouth is very much reduced in size, and the ingestion of food 
is performed by means of suction through the much modified mandi- 
bles, the process being facilitated by the powerful digestive action of 
the saliva. Under natural conditions the larvæ eat only living animals, 
but in captivity they will also take pieces of meat. The zaliva has a 
marked poisonous action, killing other insects, and even tadpoles of 
twice the size of attacking larve, very rapidly. The larvæ not only 
suck the blood of their victims, but absorb the proteid substances. 
Drops of salivary juice seem to paralize the victim and to ferment the 
proteids. The secretion is neutral, the digestion tryptic. Similar 
extra-oral digestion seems to occur in larvæ of ant-lions, etc., and 
? Biol. Centralbl., XVI, 1896, 51-57, 103-112, 
