Notes on 1)1 sect IroroK-s CoJcopfera. 175 



len of Compositiji^ and the remains of a plant-louse were 

 the only elements noticed. 



Megilla maculata. — Three specimens of this species 

 were dissected, — one received from Mr. Webster in May, 

 one from Mr. McBride in July, and one taken at Normal 

 in September. The specimen from Mr. Webster was cap- 

 , tured on the flowers of dandelions. Its entire alimentary 

 canal was closelj^ packed with hexagonal, spinose pollen 

 cells, doubtless taken from that plant. A second had 

 eaten the anthers and pollen of grass with a few spores of 

 Myxogastres.* The third specimen contained pollen and 

 fungus spores in about equal quantities. While these 

 Coccinellidce had made good their usual reputation as 

 enemies of plant-lice, it should be noticed that these con- 

 stituted only about ten per cent, of their food. 



If these specimens of the various families of predaceous 

 beetles are fair examples of their class, the above facts 

 imply that the individual carnivorous insect is much less 

 valuable than has usually been supposed, while predace- 

 ous insects as a class are much more beneficial. If these 

 species are predaceous, as a rule, not more than from one- 

 fourth to one-third of the time, the injury done by the de- 

 struction of one of them is very much less than if they 

 were, as is usually supposed, almost wholly carnivorous. 

 But, on the other hand, if they can live on the soft parts 

 of plants when animal food becomes scarce, their numbers 

 will be maintained at a far higher figure than would be 

 possible if they were dependent upon animal food alone. 

 Preferring animal food to vegetable, as they doubtless do 

 when equally obtainable, they operate as a much more ef- 

 fective check on the undue increase of other insects than 

 if their number were at all times strictly limited by the 

 numbers of their food species. We should remember, in 

 this connection, that we cannot ordinarily expect of any 

 predaceous animal that it will do more than to eliminate 

 the excess of the species it preys upon, keeping their num- 

 bers down within certain constant limits. As a prudent 

 sovereign finds it worth while to maintain a much larger 



*BurriU. 



