THE PRACTICAL ENTOMOLOGIST. 



125 



I. Tenthredo ribia Schrank. Quoted by Dahlbom Clav. 

 hymen, si/stem. p. 36. Said by Dufour fp. 576) to belong to 

 the genus Coryna of St. Fargeau, which is a pre-occupied 

 Bynonym of the subgenus Tenthredo of Hartig. (See 

 Brulle Hymen, p. 61)4.) Larva unknown to Dahlbom. 



The larva of what is apparently the same insect, though 

 Dahlbom refers it to his Ncmaiiis grossulai-i(E, is figured 

 by Reaumur (V. p. 94 and Plate 10) as Za/ausse chenille 

 dugroseillier (the false caterpillar of the currant and 

 gooseberry), and is described as 22-footed, (like the larvre 

 of most Tenthredo,) and as having no hairs proceeding 

 from the black tubercles always found on the body be- 

 fore the last larval moult. See Dufour, p. 576. 



II. Nematus [tenthredo] ventricosus King, Berlin Ma- 

 gazin, A. D. 1819. The jjcrfoct insect only described? 

 Quoted by Snellen von Vollenhoven Zijdscrift Entoin. 

 1859, as the authentic name of the species, the larva of 

 which was in 1834 described by Bouche. Overlooked by 

 Dufour. 



Nematus [tenthredo] affinis St. Farg. % and Nematus 

 [tenthredo] 3-marulatus St. Farg. 9 , Monogr. Tenthr. p. 69, 

 A. D. 1823. Evidently described from the jierfect insect 

 only. Quoted by Dufour as identical with his species. 



Nematus [tenthredo] ventricosus Klug. The larva is de- 

 Bcribed by Bouche Naturg. Inseckt. p. 140, A. D. 1834, as 

 bristly and with black tubercles, the dorsal ones *' most- 

 ly on each segment in three transverse rows." His de- 

 scription evidently applies only to the larva before its 

 last larval moult, after which it always, or at all events 

 often, loses the tubercles and hairs and becomes entirely 

 green ; for he gives the length of the larva as only seven 

 lines. It is said to swarm upon both Currant and Goose- 

 berry bushes. Entirely overlooked by Dufour. 



Nematus grossularice Dahlbom. (1. c.) A. D. 1835. Lar- 

 va said to be 20-footed, and with hairs proceeding from 

 the dark tubercles always found on the body before the 

 final moult. Also said to change to green after the last 

 moult. On Gooseberry. Quoted by Dufour. 



Nematus gross^dariatus Dahl. {Ibid.) Also on Goose- 

 berry. Supposed by Dahlbom to be a distinct species, 

 although he says himself that the perfect insects are as 

 like as one egg to another, merely because the larva spins 

 its cocoon on the leaves of the infested plant, instead of 

 going underground to do so. M. Dufour found some of 

 his larvfe to do the very same thing, although they all 

 produced the same imago, (pp. 572 — 3.) Hence he very 

 justly infers thaX grossulariatus is a mere synonym. We 

 might as well make two species of the Wheat-midge 

 (Diplosis tritici Kby.), because some few of the larvEe con- 

 Btruct their cocoons in the ear of the wheat, instead of 

 going underground for that purpose. 



Nematus ribesii Stephens, III. Brit. Eni. Mand. VII, p. 

 32. A. D. 1835. Description very imperfect, the larva 

 not being described, and nothing being said as to which 

 Bex of the perfect insect is described. On Red Currant. 

 Entirely overlooked by Dufour. 



Nematus ventricosus Klug. Hartig Aderfl. Deutseh. I, p. 

 196, A. D. 1837. 



Nematus ribis Leduc, Mem. Soc. Sc. Natur. Seine-et-Oise 

 II, Plate 1, fig. :'., Plate 2, figs. 1—2. A. D. 1846 ? On 

 White and Red Currants. Quoted by Dufour. 



Nematus ribis Leduc apud Dufour, 1. c. A. D. 1846. On 

 Red Currant. M. Dufour describes the larva before its 

 last larval moult so as to agree exactly with Bouch^'s de- 

 scription, except that Bouche says nothing of the anal 

 plate being black. In particular he says that "each seg- 

 ment has three rows of black tubercles transversely ar- 

 ranged ;" (p. 674:) which, by the way, is not strictly 

 true of the three thoracic segments in our New York spe- 

 cies. 



M. Dufour assigns the following reasons (p. 577) for he- 

 \\e\mg\\\s Nematus ribis to be distinct from Dahlbom's 

 N. grossularice : \st. He says that his larva lacks the two 

 anal prologs and is 18-footed, not 20-footed. But he al- 

 lows (p. 674), that there is a bilobate projection on the 

 anal segnient, which is used by his larva to walk with, 

 and this is about all the anal proleg that I have seen on 

 any JVemadw larva. 2nd. He finds in his larva, before 

 its last larval moult, a dark plate with pointed angles on 

 the dorsum of the last segment, which Dahlbom says no- 

 thing about. As this plate is expressly said to disappear 

 afterwards, it might likely enough have escaped Dahl- 

 bom's notice. It is very obvious in our American New 

 York larva. 3ro!. Dahlbom describes the tubercles on 



his immature larva as piceous-black, and Dufour says 

 they are coal-black in his. This is splitting hairs with 

 a vengeance. 4M. Dufour finds no trace in his larvae of 

 a dorsal green line described as existing in Dahlt)om's 

 larvee. The ground-color of the larvte being pale green, 

 and '*the middle tubercles on the back forming two rows," 

 as Bouche correctly states in his description, this is 

 scarcely worth talking about. 5/^. Dufour says that there 

 is a notable diSereuce in the distance between the eyes 

 of the two larvae, (une difference notable de tailte entre les 

 yeux.) This is probably based upon Dahlbom's figures, 

 which may be not perfectly correct, dth. Dahlbom's 

 larva fed on the Gooseberry and Dufour's on the Cur- 

 rant. But our American insect, as has been shown 

 above, feeds indiscriminately upon both plants; and 

 Bouche expressly states that ventricosus Klug occurs "in 

 two generations in May and then again in July and Au- 

 gust, on Gooseberry and Currant bushes, which they often 

 eat up almost entirely." 1th. Dahlbom describes the co- 

 coon of his species as having an external envelop of thin 

 network. Dufour can see in his cocoon only "filaments 

 which seem to cross one another on its flanks to fix it to 

 its place." (p. 679.) This is a distinction almost without 

 a difference. As regards the perfect insects, it is not 

 stated that there is any difference whatever. 



M. Dufour contends that descriptions must be rigor- 

 ously interpreted, without making any allowance for va- 

 riations, whether geographical, phytophagic or otherwise, 

 or for possible oversights or inaccuracies in the describer. 

 But that even M. Dufour himself is sometimes inaccurate, 

 may be inferred from the following facts: — 1st. He de- 

 scribes the wing-scales of his insect as "black" and the 

 ground-color as "luteous or luteo-rufous;" (p. 679;) where- 

 as it is contrary to the general law of coloration in Ten- 

 thredinidoe, that the wing-scale should ever be black ex- 

 cept where the body is almost entirely black. In our 

 American insect it is luteous in both sexes always. 2nd. 

 He says that in his larva the abdominal prologs "occupy 

 the six segments which follow those of the thorax;" (p. 

 574 ;) whereas in all Tenthredinidous larvae, even in those 

 which are 22-footed, the segment immediately behind 

 the thorax is always destitute of prolegs. 



Nematus [Selandria] ribis Winehell. Am. Jour. 8c. Arts, 

 Sep., 1864, p. 291. Like Bouche, this author in his de- 

 scription has entirely overlooked the normal or occasion- 

 al change in the larva, after the last moult, from green 

 dotted with black to pure green, and like Dufour and 

 Stephens, he states that it feeds on the Red Currant, with- 

 out being aware that it also feeds on the Gooseberry. 



[From a Letter from Isaac Hick.s, N. Y.] 

 We want your Paper to go ahead, so as to expel 

 all such errors as boring into trees and putting in 

 sulphur. In 1860, having heard of this sulphur 

 humbug, and thinking it would be but little trouble 

 to try the experiment, I bored about six half-ineh 

 auger holes into my peach trees. Well, they lived 

 a few years, bore a few peaches, and the effects of 

 the Curl and Yellows soon sent them to the woodpile. 

 One day my man called me in great earnestness to 

 come there quick to the woodpile; he had some- 

 thing wonderful to show me. And sure enough 

 he had been cutting up the trunks of my unfortu- 

 nate peach-trees, and had come across the auger- 

 holes made four or five years previously and filled 

 with sulphur. It was perfectly incomprehensible 

 to him, how that yellow stuff ever got there. Now, 

 as these trees lived several years after they had 

 been bored and the holes filled with sulphur, and 

 as the sulphur was still there when they were cut 

 up for fuel, it is plain that the sap cannot take up 

 the sulphur and carry it away, out of the auger- 

 holes in which it was originally placed, into the 

 branches, twigs and leaves ; which is assumed to be 

 the case by the believers in the " Sulphur-cure." 



