64 MASSACHUSETTS HORTICULTURAL SOCIETY. 



destroying one insect are used for an entirel}' different one, or the 

 remedy is applied too early or too late, creating distrust of entomo- 

 logical knowledge. At times insects appear in great numbers which 

 have never appeared before. Most of our destructive insects are 

 imported from Europe, and have driven out the native kinds, as 

 foreign weeds have superseded the indigenous. American insects 

 are of a more ancient and less improved t}^e than the European, 

 and can no more cope with civilized European insects than the red 

 man can cope with the white man. 



Mr. Mann reviewed a recent publication upon the subject of his 

 lecture, to show that neither exi^erience in horticulture nor in any 

 other walk of life, would avail for the protection of plants from in- 

 jury by insects, unless a knowledge was gained of the insects them- 

 selves, and that any number of isolated observations, however ac- 

 curate in themselves, might lead, as in the case mentioned they had 

 led, to the most erroneous conclusions, imless that thread of inter- 

 pretation was seized upon, which could only be grasped with cer- 

 tainty by persons who had made the insects themselves objects of 

 study. 



He then gave an account of the principal insects known to be in- 

 jurious to currant bushes in this part of the country, pointing out 

 their differences in appearance and in habit, and the different mea- 

 sures necessary to adopt in order to prevent or diminish the injury 

 caused b^^ them. 



1 . The tender tips of the currant bushes are cut off squarely in 

 the night by the caterpillar of a moth known as Hadena arctica, a 

 description of which ma}^ be found in Dr. Harris' " Treatise on 

 Insects Injurious to Vegetation," edition of 1862, p. 450. This 

 caterpillar is not known to cause any other injury to the currant 

 bush. 



2,3. The cater})illars of two insects, one a moth, ^geria tipu- 

 Uformis, and the other a beetle, Psenocerus supernotatus^ con- 

 sume the core of the stems, weakening the plant both in its power 

 of work and in its power of resisting breakage, or quite killing it. 

 These insects are best attacked by breaking off in winter the stems 

 containing the chr^^salis and burning them. 



4, 5. The caterpillars of two other insects, one a moth. Miopia 

 ribearia, and the other a saw-fly, Nematus ventricosus, consume 

 the leaves of the plant, thus checking or destroying the growth of 

 the fruit and eventually that of the whole plant. The former of 



