72 



THE PRACTICAL ENTOMOLOGIST. 



fact, that a neighbor of yours whose potatoes have lonr; 

 been afflicted in tliis manner, "says that he introduced 

 the disease upon his farm in seed-potatoes, procured from 

 a distance about 10 years ago." 



According to your account, this "scab" was "first no- 

 ticed in Delaware about 10 years ago, is now widely-spread 

 and is increasing every year, and if not checked, will 

 eventually ruin the potato crop." I have little doubt 

 that, as you suggest, is was to this disease that Mr. Thos. 

 Cnnard, of Pennsylvania, referred, when he said that 

 "his potatoes were badly nibbled by some bug or worm, 

 and often almost ruined;" (See Practical Entomologist, 

 I, p. Ill;) though I erroneously xinderstood him to refer, 

 not to the tuber but to the leaf of the potato. Of course 

 the " Three lined leaf-beetle" of the potato (figured Prac- 

 tical EvTOMOLOGisT II, p. 2o,)can have nothing to do with 

 causing your "scab ;" more particularly as you say, tliat 

 yen '• uo not think there were over 200 of thelarvse of this 

 beetle last year in about two acres of your potatoes, the 

 vines growing luxuriantly;" and yet that " two-thirds of 

 your potatoes are as scabby as the specimens sent," tlie 

 tubers thus affected being ** generally the smallest on the 

 vine and evidently stunted by the disease." 



It is, of course, impossible to indicate any certain reme- 

 dy for this " scab," till we know for certain wliat causes 

 it; and if it is caused by an insect, what are the habits 

 of that insect. Until I can institute further and fuller 

 investigations, I can only guess and grope round in the 

 dark. But supposing my guess to be a correct one, I 

 should recommend your farmers not, on any account, to 

 plant any scabby potatoes, and not to keep any on hand 

 or allow any to be about in the open air after spring opens. 

 In cutting potatoes for seed, the scabby part should bo 

 removed and destroyed; and wherever possible, let the 

 potato patch be located a considerable distance from last 

 year's patch. By this means the multiplication of tliis 

 Potato-gnat may be measurably checked ; and if the gnat 

 does really cause the scab, the scab will also be checked. 



I should be obliged by your mailing me a dozen or two 

 freshly cut specimens of your " Scab," packed in any 

 tight little tin-box. The two already sent were as dry as 

 tinder and pressed as flat as a pancake; and on soaking 

 them in hot water to restore them to something like their 

 natural condition, the larvfe got killed. I am very de- 

 Birous to breed a parcel of these larvpe to the fly state this 

 season, so as to complete thehistory of the insect at as early 

 ' a date as possible. As to the gapes in Chickens, see the 

 Answer to Milton Conrad in thelast number of the Phac- 



TICAL E.VTOMOLOGIST, (p- 50.) 



E. Daggy. Illinois. — The mass of eggs which you found 

 on the branch of a plum-tree, are, I think, those of the 

 moth of the Apple-tree " caterpillar," (Clisiocampa ameri- 

 cana.) Besides the Apple-tree, this moth lays its eggs 

 upon the Cherry, the Willow, the Birch, and several other 

 trees; yet, strange to say, though the Pc;ir is so closely 

 allied to the Apple, all accounts agree that it never in- 

 fests Pear-trees. Almost universally the eggs of this in- 

 sect completely surround a small twig; but in the speci- 

 men sent, which was on a branch, they only reach about 

 half way. round. Possibly, therefore, they may be the 

 eggs of another species of Clisiocampa ( CI. syhatica, ) 

 which is occasionally found on apple and cherry trees, 

 and the eggs of which have not hitherto been observed. 



C. II., Illinois. — The eggs which you send as found both 

 on pear and apf)le twigs, are thtise of the common Caty- 

 did, and precisely similar to those noticed in the Answer 

 to Geo. Haines in the last number of the Practical Ento- 

 mologist. I know from personal observation that our Caty- 

 dids sometimes eat flies. Whether they feed almost ex- 

 clusively on such diet, I do not know; but I incline to 

 believe that they do. Otherwise, if they feed almost en- 

 tirely on the leaves of the trees upon which they are 

 found, what is to prevent them from occasionally appear- 

 ing in vast swarms, as our common Grasshoppers do, and 

 as certain wingless Catydids also do, which are known in 

 California and the Rocky mountain region to have the 

 same habits as Grasshoppers? All previous writers, how- 

 ever, have assumed, that all the species of the Catydid 

 family feed exclusively upon vegetable substances. On 

 the general principle that wo ought not to destroy life 

 wantonly, I should be inclined myself to let these eggs 

 alone, wherever I found them. 



Henry Morey, Illinois. — ^I cannot tell from your descrip- 

 tion what the "caterpillars" were, of which you found eo 



many " nests" on the wild cherry, in the latter half of 

 July. The caterpillar of a white moth, the Ilyphantria 

 tcxtor of Harris, often makes web-nests on that trei*, and 

 siunetimes on apple-trees, but much more generally on 

 the Pig-nut Hickory, about that tinie of the year. But 

 that is a I6-footed larva, not very unlike the common 

 " caterpillar" of the apple-tree, except that it is only Iialf 

 as large : and you describe yours as without any legs at 

 all, and as having " two spines at one end and four at the 

 other, black and about 1-16 inch long." You say nothing 

 about the size or color of your " caterpillars," or about the 

 kind of" nests" in which they lived ; and if your descrip- 

 tion be correct, they cannot be " caterpillars" in the en- 

 tomological sense of the term, i. e. the larvte either of 

 butterflies or of moths. Please send specimens next 

 summer. 



Peter Ferris, N. Y. — The egg-bunches on your apple- 

 tree twigs belong, there can be little doubt, to the cater- 

 pillar which devastated the orchards in your neighbor- 

 liood so terribly last year. They are clearly distinct from 

 those of the common tent-caterpillar i Clisiocampa nnieri- 

 cana), and, in spite of your belief to the contrary, I can- 

 not help strongly suspecting that they will turn out to be 

 those of the Forest tent-caterpillar ( Clis. sylvatica), which 

 ordinarily infests forest trees, but has been known some- 

 times to swarm on apple-trees. But in any case, time 

 will soon solve the problem, as I exj^ect to hatch i:)Ienty 

 of larvsB from the eggs sent, which arrived in e.xcellent 

 order. Your neighbors are doing the very wisest possible 

 thing, by gathering and destroying these egg-bunches, in 

 order to rid themselves of the plague of caterpillars next 

 year. As you say that from 50 to 100 egg-bunches are 

 often formed on one tree, it is evident that, if left undis- 

 turbed, that quantity of eggs would produce caterpillars 

 enough to strip the entire tree of every green leaf. 



The double row of eggs so beautifully arranged in two 

 parallel rows on an apple-twig are quite new to me. They 

 are certainly not the eggs of any Grasshopper or Catydid; 

 and I think they will ]>rove to be those of some true Bug, 

 (Order Heteroptera,) as they strongly resemble those of 

 Xabisfcra, a Canibal Bug found on grasses and the cere- 

 al plants. There are several kinds uf the large stinking 

 Bugs often found on blackberries and raspberries, which, 

 as I have shown, habitually feed on caterpillars; and I 

 should not be surprised if these eggs belong to some of 

 these. I shall probably, however, breed from them, in 

 which event I will let you know the result. They can 

 scarcely be the eggs of any moth ; as I know the eggs of 

 all the species commonly found on the apple-tree. 



M. M. S., Penna. — In reply to your three questions: — 

 \sl. I do not think that the darker or paler coloration in 

 Attacus Polyphemus is caused by the food-plant. You say 

 that those you fed one summer on honey-locust were, 

 when the moths emerged, " of a clear pretty buff color," 

 and those you fed another summer on silver maple, *' of 

 the usual color, dark or grayish." I have four specimens, 

 all bred by myself from the oak, now before me, and they 

 vary in coloration about as much as your language would 

 seem to indicate. Similar variations occur in Attacus r.e~ 

 cropia. 2nd. The "brown woolly bears," which you speak 

 of as often walking about in the winter, are, I suppose, 

 the larvoB of Arctia isabclla, which are brown-black at 

 each end, and tan-red in the middle. Like several other 

 lepidopterous larvae, which often, on that account, puzzle 

 young breeders of insects, these pa.?3 the winter in the 

 larva state, and "feed up," as it it is technically term- 

 ed, in the spring; i. e. go to eating a second time in the 

 spring, so as to complete their full larval development. 

 When you see them wandering about on warm winter 

 days, they are not, as you suppose, "homeless and objeet- 

 h'ss,with no goal in view, draggingouta forlorn existence," 

 but they are diligently and industriously searching for 

 some stray blade of grass or small weed which, under the 

 protection of the snow, has retained its greenness through 

 the winter. They usually with me spin up early in May, 

 and come out as moths some time in June. Srd. The 

 moths which you bred from green larvic feeding upon 

 maple, were jjndoubtedly Dryocampa rubicunda. You 

 will find a figure and dos'eriptinn of it in Harris's Injuri- 

 ous In.'sccts. p. 408; and a description of the larva, which 

 fiMuU exclusively on ma)de ami was unknown to Harris, 

 from the pen of Mr. Lintner in the Proceedings ic. Ill, 

 p. 426. The larva, as you correctly suppose, does not spin 

 a cocoon, but goes underground to change into the pupa 



