176 



destroy great numbers of plant-lice, Aiihides^ and when older, they prey 

 upon caterpillars, or indeed upon any other insect they can overpower. 

 They kill their i^rey by inserting- the proboscis into it, and which emits a 

 most powerful poisonous liquid into the wound. The victim thus pierced 

 dies in a very short time. Thej" then leisurely suck the juices out, and 

 drop the empty skin. The perfect wheel-bug is a large and very singu- 

 lar looking insect, of very slow and deliberate motions when undisturbed, 

 and stealing up to its prej'. It is of a gray color, and has a high semi- 

 circular ridge or projection on the crest of its thorax, armed with nine 

 perfectly arranged teeth, or cog-like protuberances, like very short 

 spokes or cogs of a wheel ; hence the vulgar name of wheel-bug. The 

 young shed their skins several times before attaining their full size. As 

 this insect is constantly employed, from the moment it is hatched, in 

 searching for and destroying noxious insects, it may be considered a 

 friend to the horticulturist and farmer. A dozen or so of these insects, 

 placed near the nest of some of those caterpillars so destructive to our 

 fruit and forest trees, will destroy almost every caterpillar in it in a 

 short time, as they are exceedingly voracious, and each insect will de- 

 stroy several caterpillars daily. Great care must be taken, however, 

 when handling the adult insects, as they are very apt to sting, or rather, 

 insert their strong curved beaks into the naked flesh, and the poisonous 

 fluid ejected, when the wound is inflicted, is extremely powerful, and 

 much more painful than the sting of a large wasp or hornet. One of 

 these insects having stung the writer, the pain lasted for several hours, 

 and was only alleviated by apiilications of ammonia. Several days af- 

 terward, the flesh immediately surrounding the puncture was so much 

 poisoned that it sloughed off, leaving a small hole in the injured thumb. 



CHEMICAL MEMORANDA. 



By William McMurtrie, Chemist. 



SuaAH COKN. — The difficulties accompanying the prosecution of proxi- 

 mate organic analysis of sugar-corn may have been considered sufficient 

 cause for our failure to find upon record any reliable statement concern- 

 ing its composition, but it appears to be a fact that chemists have thus far 

 either avoided it or have failed to come in contact with it. When called 

 upon a short time ago by Mr, T. Worthington, of Morrow, Warren County, 

 Ohio, for information concerning its composition and comparative value 

 as a material for the manufacture of alcoholic liquors, we found it neces- 

 sary to resort to analysis to determine the facts desired. 



The- method employed in our analyses was essentially' the same as 

 that made use of in previous analyses of corn as published in the 

 Annual Eeport of this Department for 1873, the only difference being 

 a slight modification iu the separation and estimation of gum and 

 dextrine. Methylic alcohol dissolves dextrine without attacking gum, 

 and we therefore employed it in their separation. 



For comparison we have also made an analysis of a sample taken from 

 a lot of corn held by this Department for distribution. There seems to 

 be considerable difference in the composition of these two samples, but 

 this may naturally be expected on account of the different qualities as- 

 cribed to the several varieties of this kind of corn. The sweet taste is 

 evidently due to the high percentage of dextrine it contains, and we 



