326 REPORT OF THE COMMISSIONER OF AGRICULTURE. 



the gall-inhabiting mother. 3. The female egg from the winged mother, 

 rather more elliptical and 0.4 ram long when matured. 4. The male egg 

 from same, J less in length and rather stouter. 5. The impregnated 

 egg 0.32 mm long, still more ellipsoidal and with peculiar sculpture and 

 anal point. We have also the peculiar spectacle of an egg from the 

 winged mother increasing from 0.34 mm (its size when laid) to 0.4 ,,,m (its 

 size just before hatching), giving birth to a perfect insect 0.4 UUU long, 

 and this without any nourishment, laying an egg 0.32 Inm long. A 

 being thus born, and without food whatsoever, lays an egg very nearly 

 as large as that from which she came. 



"We have, further, the spectacle of an underground insect possess- 

 ing the power of existence even when confined to its subterranean re- 

 treats. It spreads in the wingless state from vine to vine, and from 

 vineyard to vineyard, when these are adjacent, either through passages 

 in the ground itself or over the surface; at the same time it is able in 

 the winged condition to migrate to much more distant points." 



The recent advance in our knowledge of the life-history and habits 

 of species has been great, but leaves yet an immense field for future 

 research. 



Insects probably outnumber in species all other animals combined, 

 some 350,000 having already been described, and fully as many more 

 remaining yet to be characterized. The proper and conscientious char- 

 acterization of a genus or species of some microscopic creature involves 

 as much labor as that of one of the higher animals. Of the above num- 

 ber a goodly proportion are injurious to cultivated crops. Lintner re- 

 cently records no less than 176 affecting the Apple. 



Of insecticides any number of substances have been recommended 

 and many of them tried with more or less satisfaction. Of these may 

 be mentioned lime, sulphur, soot, salt, wood-ashes, corrosive sublimate, 

 naphtha, naphthaline, turpentine, alum, carbolic acid, phenyle, cyanide 

 of potassium, blue vitriol, ammonia, alkalies, benzine, vinegar, sul- 

 phuric acid, quassia, vitriol (the sulphate of copper), hot water, &c. 

 Most of these may be successfully used for specific purposes, either dry. 

 in liquid, or in vapor ; but the three most useful insecticides of general 

 application in use during the early days of economic entomology in this 

 country and up to within a few years, were undoubtedly tobacco, white 

 hellebore, and soap. Tobacco-water and tobacco-smoke have long been 

 employed against Aphides and other delicate insects, and are most use- 

 ful. A quite recent advance in its use is by vaporizing. The vapor of 

 nicotine is most effectual in destroying insects wherever it can be con- 

 fined, as in greenhouses. Thus the boiling of tobacco in such a green- 

 house is as effectual as and less injurious to the plants than the 

 older methods of syringing a decoction or of fumigation by burning; 

 while experience by Mr. William Saunders at the Department of Ag- 

 riculture during the past two summers shows that the vapor gradually 

 arising from tobacco-stems strewn on the ground and regularly moist- 

 ened is likewise effectual. 



White hellebore, either dry or in liquid, has long been one of the 

 most satisfactory insecticides against Tenthredinid larvae, otherwise 

 known as false-caterpillars, of which the Imported Currant- worm (Xe- 

 mat us ventricosus) is a familiar type; while soap, syringed in strong- 

 suds, will kill some soft-bodied plant-destroyers, and when used as a 

 paint on the trunks of trees is an excellent repellant against the par- 

 ents of different borers. 



Transcending in importance, however, any of these older insecti- 

 cides are the three now most commonly used because most satisfactory. 



