THE PRACTICAL ENTOMOLOGIST. 



on record of a noxious insect travelling from the 

 west towards the east. 



But, it will be asked, where does this insect come 

 from 1 And how does it happen that it did not 

 trouble the Iowa farmers before 18Gl,and the Illi- 

 nois farmers before 18G4? I believe that I can 

 explain this satisfactorily. Unlike several other 

 noxious insects, it is not a general feeder, but 

 is confined to plants belonging to the botanical 

 family Solanacese, and especially to the genus 

 Solanum, which includes the Potato, the Toma- 

 to, the Egg-plant, and a weed called the Horse- 

 nettle, found more usually in the Southern States, 

 but which also grows in certain localities in Iowa.* 

 In 1864 Dr. Velie, the ornithologist of Rock Island, 

 111., and Dr. Parry, the botanist of Davenport, la., 

 both saw this insect iu very great numbers in Colo- 

 rado, feeding upon a wild species of Solanum — the 

 rostratum of Dunal — which is peculiar to that re- 

 gion of country and is not found east of the Mis- 

 sissippi River; and to the former gentleman I am 

 indebted for numerous specimens collected by him 

 on this plant, which are undistinguishable from 

 those found on the potato. Assuming, therefore, 

 that this wild Solanum is the natural food of the 

 insect, and that the region of country bordering 

 on the Rocky Blountaina is its natural home, its 

 range would for a long series of years be limited 

 by the range of the plant that it feeds on. But in 

 process of time civilization marched up to the Rocky 

 Mountains — potatoes were planted in Kansas and 

 Nebraska and Colorado — and the insect discovered 

 that one species of Solanum was about as palatable 

 as another. Having thus acquired a taste for pota- 

 to leaves, it would naturally spread eastward from po- 

 tato patch to potato patch, till it overspreads Iowa 

 and finally overleaped the Mississippi into Illinois. 

 In confirmation of this theory, R. W. Ilazen of Fre- 

 mont, Dodge Co., Nebraska, says that " the potato 

 bug which is so destructive in that region was first 

 discovered in 1859, about 100 miles west of Omaha 

 City, whence they have been marching eastward 

 annually."— (iV; Y. Sem. Tribune, July 18, 1865.) 

 From Omaha City to Rock Island is over 200 

 miles; so that, if the above statement be correct, 

 it appears that the insect has travelled about SCO 

 miles in six years, or at the average rate of sixty 

 miles a year. At this rate of progress it will reach 

 the Atlantic in about fourteen years. 



It may perhaps be worth stating here, that my 

 own experience is that these insects prefer the Egg- 

 plant to the Potato, and it is well known that they 

 prefer the Potato to the Tomato. Now the Egg- 

 plant is botanically more closely related to the So- 

 lanum rostratum, on which this insect feeds in 

 Colorado, than is the Potato, the two former being 

 covered with thorny prickles and the latter being 

 smooth ; and on the other hand the Potato is mucli 

 more nearly related to the Solanum rostratum than 

 is the Tomato, which last has by modern botanists 

 been removed from the genus Solanum and placed 



* Mr. Terry of Crescent City, Iowa, states that in his 

 neighborliood it attaclted tlxo Ilorse-nettle in 1863. — 

 (frairie Farmer, June 6, 186a, p. 356.) 



in a genus by itself. It would seem, therefore, that 

 the closer a plant comes to the natural food-plant 

 of the insect, the better the insect likes it. 



Dr. Fitch, in his Article on this Insect, published 

 in the Transactions of the New York State Agri- 

 cultural Society for 1863, (pp. 796—801,) asserts 

 that " it has fallen upon the potato-vines in nume- 

 rous places all over the North Western States," and 

 Mr. Cyrus Thomas, as quoted by Dr. Fitch, says 

 that " it was found in abundance in Southern Illi- 

 nois" previous to 1861. But both these gentlemen 

 confound together two perfectly distinct, but very 

 closely allied species, the Doryphora juncta of Ger- 

 mar and the Doryphora 10-lineata of Say, one of 

 which was really found in South Illinois previous 

 to 1861, while the other was not, and one of which 

 has never been known to attack the potato while 

 the other habitually does so. The former of these 

 was first described by Germar in 1824 from speci- 

 mens which he had received from Georgia, and 

 was also received by Dr. LeConte from the same 

 State ten or twelve years ago. In 1854 Dr. Hel- 

 muth of Chicago took this same species near Cairo, 

 111.; and in 1861 Mr. Chas. Sonne of Chicago cap- 

 tured very numerous specimens of it in Efiingham 

 Co., 111., on hickory bushes, which they appeared 

 to him to be feeding on. The latter species, which 

 is the true potato bug, was never taken by any one, 

 so far as I can find out, east of the Mississippi river 

 till 1864, and was first discovered by Say in 1823 

 in the regions bordering on the Upper Missouri 

 river, and is quoted by Dr. LeConte and Rogers as 

 being peculiar to Texas, Kansas and Nebraska. 

 That Dr. Fitch has confounded these two insects, 

 is proved out of his own mouth ; for he expressly 

 states that they are synonymous, {Trans., &,c. ip. 

 797.) although seven years before he wrote Rogers 

 had pointed out the principal distinctions between 

 them. (Proc. Acad. Nat. Sc. 1856, p. 30.) That 

 Mr. Thomas must have confounded them, is indi- 

 cated by the fact, that he says that his species 

 " occurs in South Illinois only on worthless weeds 

 and low shrubs, and here it has not proved injuri- 

 ous to useful vegetation" ; whence he infers " that 

 it is only accidental that it has fallen upon the po- 

 tatoes" in Iowa, and that " some peculiarity of the 

 plants, state of the atmosphere, or other influence 

 may next year cause it to forsake the potato and 

 take up its residence upon some other plant." — 

 (Trans., &c. p. 797.) 



So closely indeed do these two insects resemble 

 one another at first sight, that the Melsheimer Cata- 

 logue in 1853, and probably Thos. Say in 1824, 

 considered them as mere varieties of one and the 

 same species. Yet each has its own peculiar cha- 

 racters — each was originally confined to a distinct 

 region of country — and one of them, at all events, 

 and probably both, are limited to a distinct botani- 

 cal family of plants and can feed on no other. For 

 the benefit of those who are curious in such mat- 

 ters, I subjoin a table of the principal points of dif- 

 ference between the two species, which has been 

 drawn up from a comparison of numerous speci- 

 mens of each. 



