THE THREE-LINED LEAF-BEETLE: HAUITS AND REMEDIES. 135 



According to Dr. Harris, the eggs require about two weeks for hatch- 

 ing,' and the insect passes about the same length of time in its larval 

 and pupal states, but it does not appear that these periods had been 

 accurately observed. 



Dr. Fitch has expressed his belief that there are more than the two 

 annual broods ascribed to it by most writers, viz. : the beetles appear- 

 ing early in June, and again toward the end of July and early in August. 

 He had noticed their presence in potato fields throughout the season, 

 together with the larvre in various stages of growth, from which it was 

 '' evident that they are not periodical, but are continually coming forth, 

 one after another, and depositing their eggs from the commencement of 

 their operations in June until the chilly nights of autumn suspend their 

 work." This would conform to the continued reproduction of the 

 successive broods of the asparagus beetle, Crioceris asparagi, to which 

 L. triliueata is closely allied — the twelve United States species of Lcjna 

 of the Crotch Check list uniting with the two of Crioceris to form the 

 Chrysomelid tribe of Criocerini. 



The Insect Sometimes Carnivorous. 



From seemingly good authority it appears that this beetle is not an 

 unmitigated pest, but that it renders some compensation for its occa- 

 sional destructiveness, in preying upon one of its associates and kindred 

 — afar greater pest. In Field and Forest for July, 1877, we find the 

 following : 



The three- striped potato-beetle, Lema trilineata, has been doing 

 good service this season in the west by destroying the eggs of the 

 Doryphora, or Colorado potato-beetle. Several correspondents in 

 Medina county, Ohio, send specimens of the insect, and report that 

 although the potato-beetles are as plenty as ever, the larvse are un- 

 usually scarce, which is attributed to " the new friend of the farmer." 

 A few were seen last year, but the present season they are very numer- 

 ous. 



As the Lema has always fed upon the foliage of the potato, it is hoped 

 that it will continue and extend its carnivorous habits. 



Remedies. 



When the insect is not very abundant, but in sufficient force to impair 

 the foliage of the plants, it may be kept within harmless limits by oc- 

 casional hand-picking, or brushing into pans of water and kerosene oil. 

 This would be more effectual in the larval stage, as the beetle is easily 

 alarmed and readily takes wing and Avithdraws itself from threatened 

 danger. 



