246 ' " REPORT OF THE COMMISSIONER OP AGRICULTURE. 



Western Diabeoticas {DiahroUca soror, Le C, and B. trivittata^ 

 Maun). — These Trestern representatives of the well-known 12-spotted 

 Diabrotica (I>. l^i-punciata) and of the striped squash-bug [D. vittata) 

 of the east have been sent to the department during the past season by 

 Mr. J. M. Dudley, of Dixon, Cal. The western species so resemble those 

 of the east that from above they cannot be distinguished. Viewed from 

 below, however, the abdomen of soror is black, while that of 12-punGtata 

 is greenish-yellow ; and the legs of trivittata are nearly all black, while 

 those of vittata are only slightly tipped with black at the joints. 



The interesting point of Mr. Dudlej'^'s communication was that the 

 specimens sent were doing considerable injury to apricots, eating into 

 the ripe and nearly-ripe fruit. From a short correspondence which ap- 

 peared in the columns of the Pacific Rural Press last fall, it would appear 

 that the injuries to fruit of various kinds from these insects have become 

 quite general, and the opinion is expressed that this has arisen from the 

 lately-introduced custom, in parts of the State, of growing certain vege- 

 tables as orchard crops ; the Diabroticas migrating to the neighboring 

 fruit after the vegetables have been destroyed. At all events, the taste 

 for fruit seems to have been recently acquired, but now that it has 

 been acquired, it seems doubtful whether the abolishing of the orchard- 

 crop system or the planting of a distasteful food would better matters 

 to any api)reciable extent. Indeed, it would be difficult to find a gar- 

 den crop which the Diabroticas would not devour, as they are very general 

 feeders. The editor of the Press says : 



So far as otir observation goes, the insect will thrive and multiply wonderfully on 

 quite a varied diet. In our garden the insect has a sharp appetite for rose-buds 

 and opening pinks, for canna and dahlia leaves, for balsam leaves and flowers, and 

 many other green and colored growths. 



The question of protecting the fruit trees from these insects bids fair 

 to become of considerable importance and also of considerable difficulty. 

 War should be made upon them wherever observed. The experiments 

 of Professor Hilgard with pyrethrum have x>roved that the powder has 

 little effect uyion these insects unless immersed in it ; that the infusion 

 ai)plied in drops failed to enter the spiracles, but that the spray was 

 very effectual. This will undoubtedly prove of use in the immediate 

 future, now that the prospects for clieai) pyrethrum are so good. 



A DESTRUCTIVE ENEMY TO SUGAR-CANE {Ligyriis rugiceps, Le 

 Conte). — Accounts have recently been received from different jiarts of 

 Saint Mary's Parish, Louisiana, of the destruction of cane by a rather 

 large black beetle, which proves on examination to be the Ligyrus ru- 

 giceps, described by Le Conte, from G eorgia, in 1856. According to sev- 

 eral correspondents, the beetle has been known to injure cane more or 

 less in different parts of the parish for twenty -five years, but it is only 

 within the last three or four years that its ravages have excited much 

 alarm ; although, in 1855 or 1856, the crop upon 80 acres of one i^lanta- 

 tion was completely destroyed by this or a similar beetle. During the 

 present year it has become destructive on many sugar estates in the 

 I)arish named; and, while in former years its work seems to have been 

 confined to the "rattoon" cane, this year many acres of both"rattoon" 

 and "plant" have been entirely ruined on some plantations. 



From specime|is which we have received, it api>ears that the adult in- 

 sects bore into the stalk just above the root, and numbers of them may 

 be found imbedded to different depths. It is said that one gentleman 

 found 45 specimens in one "15-incli section of a row." Mr. Daniel 

 Thompson, of Bayou Teche, reports tha,t in some localities the same in- 

 sect injures corn. This year the greatest injury was done very early in 



