INSECTS. 211 



IS composed of wingless individuals all alike, and all produc- 

 ing young like themselves, without the intervention of any 

 males whatever. This remarkable form of multiplication goes 

 on all summer, but in autumn a new brood of winged males 

 and females is produced. When protected from the winter, 

 however, this asexual reproduction goes on for years, no males 

 being produced. This mode of reproduction accounts for the 

 almost incalculable rapidity with which they multiply. Yet 

 their natural enemies are almost always sufficient to keep 

 them within bounds. Minute ichneumons prey upon them, 

 the young of the delicate lace-winged flies devour them, and 

 many of the lady-birds, or lady-bugs, feed upon nothing else 

 during their whole lives. Yet Professor Glover,. of the Na- 

 tional Department of Agriculture, says, that at the south 

 "Many planters imagine that these lady -birds are in some 

 mysterious manner connected with the appearance of the cot- 

 ton louse, or even that tliey are the progenitors of the aphis 

 itself. This erroneous impression is formed in consequence of 

 these insects being always found in similar situations at the 

 same time, and abounding on plants already weakened by the 

 attacks of the plant louse. The sudden disappearance is also 

 accounted for, as, with the decrease of their natural food, the 

 lady-birds also disappear and migrate to neighboring planta- 

 tions in search of a fresh supply of nutriment. I have actu-^ 

 ally known several planters who have caused them to be de- 

 stroyed by their field hands, when and wherever found, and 

 who complained that their plants were still destroyed by the 

 aphis, or cotton louse. This was only to be expected, as they 

 had destroyed the natural enerny of the louse, and suffered 

 the pests themselves to breed in peace and safety." 



The lady-birds form a family of beetles by themselves, the 

 CoccineUidce, which are among the most beneficial of insects. 

 Most of them feed upon plant lice, but others attack the 

 chinch bug ; but even in this friendly family there is one inju- 

 rious species. The squash coccinella, as it has been called, 

 Epilachna boj-ealis, belonging to a different genus from the car- 

 nivorous species, feeds, in the young state, upon the leaves of 

 the pumpkin, squash, etc., and is frequently quite injurious. 



