325 



ject that have come under oar observation. This insect has been kno\yu 

 for over fifty years, and has been particularly injurious to the cultivated 

 Ijotato since about the year 1860, when it commenced its travels east- 

 ward from the base of the Eocky Mountains, and has been steadily pro- 

 gressing since at the rate of sixty to eighty miles a year. It is now 

 reported as very destructive in Central Xew York, Pennsylvania, and 

 New Jersey, Maryland, District of Columbia, and Eastern Yirginia. It 

 is known as the Colorado or Western Potato-Beetle, or ten-lined spear- 

 man, [Borypliora decem-Uneata,) and its habits are as follows : The eggs 

 are deposited by the female, to the number of about seven to twelve 

 hundred, at intervals, during forty days, on the leaves of the potato, in 

 somewhat regularly-arranged loose clusters. In about six days they 

 hatch into larvte, and feed upon the foliage of the plant from seventeen 

 to twenty days ; they then descend into the ground, and after remain- 

 ing in the pupa state, to which the larva changes, for ten or twelve days, 

 they again make their appearance^s perfect beetles. In about a week 

 the sexes pair, and in another week the females begin to lay their eggs 

 for a second brood, thus requiring but fifty days from egg to egg again. 

 To give some idea of their powers of reproduction the Canadian Ento- 

 mologist states, that if the progeny of a single pair were allowed to in- 

 crease without molestation for one season, the result would amount to 

 over sixty millions. The insects do not die immediately after laying 

 their eggs, as Professor Daniels, of the Wisconsin University, once kepi; 

 a female alive six weeks without food, after she had laid twelve hun- 

 dred eggs. 



There is another insect, belonging to the same genus, which is often 

 mistaken for the Colorado beetle. It is, however, easily distinguished 

 from the genuine, as the second and third stripes are always united be- 

 hind, giving the appearance of a heavy black stripe ; and the edges of 

 all the stripes have but a single row of punctures ; the legs also have a 

 black spot in the middle of the thighs. Tnis insect has also been found 

 feeding upon the horse-nettle, {Solanum caroUnense,) in South Carolina, 

 and has been taken upon potatoes and egg-plants in Alabama, and was 

 particularly injurious to the latter. 



In the accompanying wood-cut. Fig. 1 

 represents the true potato-beetle, Bory- 

 phora decem-lineata ; Fig. 3, the Dory- 

 phorajuncta; and Fig. 2 is an apparent 

 cross between the two, or a variety once 

 found in the South, in which the heavy, 

 thick black line of the juncta has a very 

 fine yellowish line runningpartly through 

 it longitudinally. 



The Colorado beetle has a great many 

 foes or parasitic insect enemies that do 



much toward lessening their numbers _ 



and preventing still greater destruction in our potato-fields. It is at- 

 tacked among the beetles by Eippodamia maculata, H. convergens, R. 

 quindecem punctata, Coccinella munda and C. novemnotata, Tetracha 

 cirginica, Calosoma callidum, Harpalus caliginosus, Pasymaclius elongatus, 

 a,nd Leb in gra)id is ; among the plant bugs hyArma spinosa A. grandis, 

 Harpactor ductus, Euschistes punctipes, and Stiretrus fimbriatus. The 

 larva of a parasitic fly, Tachina doryphorw, lives in the larva of the beetle, 

 and the Polistes rubiginosiis carries it to its nest as food for its young. 

 Epicauta pennsylvanica and Macrobasis fabricii, both beetles that feed 

 upon the potato, also devour this beetle. 



