150 
NATURAL CHECKS. 
( 
Heteropus ventricosus, Newport. About the 12th of October, 1882, a 
sack of wheat infested with larvae of the grain moth was received from 
Southern Illinois, which, for want of time, was put aside for future 
inspection. On the 13th of November, while examining the grains con¬ 
taining larvae, I noticed in a lot of fifty, three in which the worms were 
dead, and on them were numbers of globular, yellow objects, which 
proved to be a species of mite Heteropus ventricosus , Newport. Know¬ 
ing nothing of the predaceous habits of these mites, and the limited 
literature at hand throwing little light upon the matter, I did not pay 
much attention to the fact of their occurrence, until the 12th of Decem¬ 
ber, when, upon examining one hundred grains with respect to the 
effect of heat on the larva, I found fourteen of the latter infested by 
these mites. 
In the meantime I had learned that this mite was known to be 
of predaceous habit, in both England and France, (having been first 
discovered by Newport, in 1849, in the nests of Anthophom retusa , 
collected at Gravesend, England,) and afterwards described by him 
under its present name. It had also been found in France, in 1868, 
by Jules Lichtenstein, of Montpellier, and described by him under 
the name of Physogaster larvarum. This gentleman found it in bis 
breeding cages, which it so completely overran, that, as he informs 
me, he could not for six months breed a single specimen of Hymen- 
optera, of Buprestidae, or Cerambycidae, or of some Lepidoptera. 
If it has been" found by any other persons than these, or in any 
other parts of the world, previous to its discovery here by me, I 
have not been able to find the fact recorded, 
On December 31st and January 1st, I examined one hundred in¬ 
fested grains of this wheat, which had been continually kept in 
the laboratory since it was received, and found thirty-two per cent, 
of the worms dead, infested by the mites. 
While making these examinations I frequently threw the grains 
containing infested larvae into a shallow glass dish, where they re¬ 
mained on my table until the warm weather during the latter part 
of February, when the temperature of the laboratory at night was 
much higher than it had been during the previous cold weather. 
The effect of the change was soon plainly to be seen. The contents 
of the dish began to swarm with newly developed mites, and a larva 
dropped into their midst was immediately attacked, and after that its 
life was of short duration. Larvae placed at some distance from 
the dish suffered a like infection. 
To test the matter I placed near the dish some weeds, in the pith 
of which some larvae were hibernating, and in two days the mites 
had found and destroyed them. These young mites when first 
noticed are very minute, of elongate form, and extremely active, 
running about in search of larvae; and when one is found they imme¬ 
diately puncture the skin and suck the juices. 
In a day or two the posterior segments of the abdomen begin to 
enlarge, and this process continues until the inflated, bladder-like 
abdomen becomes ten or even twenty times the size of the cepha- 
lothorax. 
