PSYCHE. (Continued fi om p. 6.) of marcellus. But I have not found. in a warm room or in the greenhouse, early

Transcription

1 PSYCHE. EXPERIMENTS UPON TfIE EFFECT OF COLD APPLIED TO CHRYS- ALIDS OF BUTTERFLIES. BY WILLIAM HENRY EDWARDS, COALBURGH, W. VA. (Continued fi om p. 6.) With every experiment, however similar It might be supposed that the application the conditions seem to be, and are intended of heat to the overwintering chrysalids to be, there is a difference in results, and would precipitate the appearance of the at present the reason therefor does not ap- summer form of P. ajax, or change the pear. For example, in 1878 the first but- butterflies so that while they had the shape terfly emerged on 14th day after removal of telamonidez they should have the coloration of marcellus. But I have not found from the ice, the period being exactly what it is at its longest in this species in nature, this to occur. I have been in the habit, with an occasional exception. Others for several years, of placing the chrysalids emerged at 19 days and several at intervals up to the 96th day after ice. In in the winter, so causing the butterflies to in a warm room or in the greenhouse, early 1879, the emergence began at 8 days, and emerge in February, instead of in March by 12 days all which came out this year and April, as they would otherwise do. But had appeared, except three belated indi- the winter form has invariably emerged viduals at 22, 40 and 50 days. In previous from such chrysalids. experiments, no matter what the species, the butterflies had not emerged till after 3. In June 1879, I obtained eggs of the natural period of the chrysalis had Grapta interrogationis, laid by form urn. passed, after removal from the ice. In brosa, in confinement. As the chrysalids this one, either the cold had not fully sus- formed, and at intervals of from 6 to 24 pended the changes which the pupa under- hours after pupation, they were placed in goes in the chrysalis, or these changes the ice box. After 14 days I removed all were hastened by some other cause after but five, which were left 6 days longer. the chrysalids were taken from the ice. Several were dead at the end of the 14 In the first experiment, apparently, the days. Temperature most of the tine about changes were absolutely suspended as long 5 F. 1.7 C.J, but a little higher for a as the cold remained, few hours each day, as the ice melted, reach-

2 16 PSYCHE. ing then 40 to 45 F. [4 to 7 C.J. I broad band of the females), which occuobtained from the 14-day lot seven perfect pies the same position as the clouding in butterflies 3 % 4 9 from the 20-day lot the normal male but blackened and somefive 4 % 1 9 every one umbrosa; and what diffused. In the four examples from nearly all had changed in one striking par- the 20-day lots this connecting band is ticular. In the normal umbrosa, of both scarcely as deep colored and continuous sexess the fore wings on upper side haves as in the other three. Beyond this change on costal margin next inside the broad on the submarginal area whereby a co,lborder of hind margin and separated spicuous band is created where naturally from it by a considerable space of fhlvous would be only the two patches and a faint a dark patch which ends a little below the cloudiness over the intervening fulvous discoidal nerwlle; inside the same border space I see no difference between these at inner angle is a similar patch lying on examples of both sexes and a long series the submedian interspace. Between these of natural ones placed beside them so far two patchess across all the median inter- as relates to the upper surface. spacess the ground is fulvouss but very On the under side all the males are ot slightly and faintly clouded with black, the same types the colors intense. There is Indeed this clouding would usually not be considerably more red both dark a)d pale noticed, over the whole surface than in the series I find that in all the four 9 exposed to ofnatural examples these latter discovering cold 14 days, there is present a broad biack shades of brown over which is a bluish or band crossing the entire wing continuouss lilaceous flush. In the females I discover of uniform shade covering the two patches no change on under side. and intervening space and almost confluent It appears that 14 days was as effective with the marginal border from end to end in producing changes in case of this Graponly a streak of obscured fulvous any- tct as t longer period. In facts the most where separating band and border. In decided changes were found to be in the the other female being from chrysalis ex- t emales exposed least. It appears also that posed 20 days the band is presents but cold will produce change if applied after while broad and covering the spce between the chrysalis has hardened. In 1878, I the patches, it is not so dark as in the other put Grapta chrysalids on ice at from 10 examples, and includes against the border minutes to 6 hours after pupation, and a series of obscured fulvous lunules. This while some were quite soft,--and lost is like some normal females, and this re- every one of them, although some chrysamale, though longest exposed, therefore is lids of/). ajax in same box, and in part essentially unchanged, exposed very shortly after pupation, were In all the males, the patches are diffuse, not injured. It also appears that. cold may those at apex almost coalescing with the change certain markings only, and that border. In the three males from the 14- the females were most susceptible to the day lot, these patches are connected by a influence. narrow dark band (very different from the The resulting butterflies were all urn-

3 PSYCHE. 17 brosa though both forms of the species ag% remained in box 2 days; three at might have been expected to appear. In 3 hours olds for 8 dayss and one age breeding from eggs laid by umbrosa in a omitteds,for 6 days. All these produced ibrmer year I obtained both forms of the arcellus and therefore they had not been butterfiy viz. 11 umbrosa and 6 fabri- affected by the cold. cii. But from this single experiment it cannot be determined whether any change {. In 1877 I had placed several chrysof form was brought about, alids of Lycaena pseudargiolus in the ice box thinking that I might thus obtain the 4. In 1877s a lot of eight chrysalids form violacea which is the winter form of of P. ajax all under 12 hours from pupa- the species. On 8 Aug. 31 days after the tion were put on ice and left there 24 days. chrysalids were removed from the box a (They were placed on top of the ice but female emerged in some respects considerin all later experiments I have placed them ably unlike either of the forms. The cornunder it in the bottom of the box.) The mon series of dark streaks and points across temperature was irregular and as I was the disks was wholly wanting though the absent from home nearly all of the time stripes across the ends of cells were presand had to leave the box in charge of ser- ent; and the marginal crescents were large vantss I felt no certainty that the ice had and black--far more conspicuous than is not been supplied irregularly or that there ever seen in the naturallaseudargiolus and had not been intervals during which there still very unlike violacea. The general was no ice in the box. :But from these coloration of both surfaces was that of the chrysalids there came 5 % 3 9 butterflies, usual female l)seudargiolus. All the other Of thes% one was telamonides unquestion- chrysalids were found to be dead. ablys in color and markings; all the rest were between telamonides and marcellus. In Can. Entom.s v. 7 p I gave Two other chrysalidss on ice 23 days in an account of the first experiments made the box at same time with the above men- by me in exposing chrysalids to cold the tioned eight gave telamonides. But three subject being /. ajax. The chrysalids more exposed 26 dayss and 1 hour from were placed in the ice box, but were subpupation when placed in tim box all gave sequently removed to the ice house and unchanged marcellus, left fbr two months after forming but on In the box at same time were 6 chrysa- returning home after a long absenee I lids of G. interrogationiss and all of them found the ice had wholly melted. The gave unchanged umbrosa, chrysalids had at first been subjected to a low temperature in the boxs but as the ice 5. During thesame seasons 1877sI ex- in the house failed the temperature had posed six P. ajax chrysalidss keeping the risen so that when I examined the tin temperature as nearly as possible at 33 F. cases which had held the chrysalids many [0.6 C.-]. One was 1 hour from pupation butterflies were found alive therein in a and remained in the box 5 days one same crippled state. About one half the butter-

4 18 PS YGHE. flies that emerged from this lot were com- partly or not at all; from the 25-day lot pletely changed being telamonides and all were changed. Temperature 33 d-f. wcdshii, and about half the rest were partly [0.6 C.J. changed. It was observed also that the In 1877: chrysalids under 1.2 hours old, butterflies were generally smaller than the but the minimum not noted; exposure 24 average marcellus. I have not been able days. Temperature 40 F. [4.4 C.] and to subject chrysalids to cold for a very long upwards, irregular. Result: one changed period, for the reason that ice fails us in fully, seven partly; some others subjected midsummer, it having been put up when to same conditions for 23 days were fully thin and of poor quality, owing to our changed; others at 26 days not at all. moderate winter climate. Indeed, in some In 1875: chrysalids stated in my note seasons we get no ice. at all, as the streams book to have been exposed as formed," do not freeze over. On more than one but the exact age not given; exposed for occasion the period ofexposure has abruptly 30 to 60 days temperature at first about terminated, and much earlier than I had 32 F. [0 C.J, afterwards uncertain. Reintended by the failure of the ice. suit: 50 per cent. fully changed, 25 per cent. partly, rest not. SUMMARY OF THE EXPERIMENTS WITH GENERAL CONCLUSIONS:--- P. aja. 1. P. ajax. The longer the exposure In 1877 chrysalids 1 to 3 hours old under a low temperature the more decided exposed from 2 to 8 days. Temperature the change, but 25 or 30 days seem quite 33 d- F. [0.6 C.]. 1Io change effected, sufficient in many cases, and changes have In 1878: chrysalids 10 to 15 minutes been produced by exposure for 20, 16 and old, and at intervals up to 1 day, and then daily to 8th day from pupation; exposure from 19 to 5 days. Result: one telamonides or walshii from chrysalis 12 hours old, 11 days exposure; one walshii from chrysalis 2 hours old, 11 days exposure one telamonides from Chrysalis 3 days old, 16 days exposure; all the rest unchanged, but the periods of emergence remarkably prolonged. Temperature 33 + s. C.]. In 1879: chrysalids not less than days; no changes recorded at less than 11 days while exposure at 8 days and less has produced no effect except in some cases to prolong the chrysalis period. 2. The longest interval between pupation and exposure to cold when any change has resulted, has been 3 days. In all instances beyond that no change has been produced. The shortest interval has been two hours, and in this instance the butterfly was changed to walshii, which is a change more extreme than to telamonides. Most chrysalids exposed so early die in the hours old nor over 24 hours; exposed 14, 20 and 24 days. Result: the period of process but as many changes have been emerging greatly precipitated in nearly all effected when the age of the chrysalis at cases. From the 14-day lot there was no exposure has been from 12 to 24 hours, I change or only a partial one from the 20- believe that to be the most satisfactory pcday lot one half were changed, the rest tied. The chrysalis has then become hard-

5 PS YGHE. 19 ened and the growth of the organs of the With P. ajax 32 to 40 F. [0 to 4.4 C.J pupa probably then begins and their direc- seems a proper temperature. tion may best be turned by the cold then My experiments with /)h. tharos are applied, given in Can. Entom. v. 9 p. 4 and p. 3. The effect of the cold is to albinize Also in Butterflies of ll. A. the butterfly the black area being con- v. 2 pt. 7. In the former a complete stantly reduced, change was brought about and every but- 4. Cold has failed to change the shape terfly emerged in the winter form. Tempof the wings its influence being confined erature about 40 F. [4.4 C.J and conto coloration and markings; the frontal tinned for 7 days the chrysalids being 3 hairs of the head have also been changed; 6 9 hours old when exposed and before and the sexes are equally susceptible, several had hardened. In the second ex- 5. Grapta interrogationis. 14 days periment the temperature was about 32 exposure aher the chrysalids have hard- F. [-0 C.]; the chrysalids were 10 minened has been found sufficient to produce utes to 9 hours old and the exposure was changes and the females were most sus- about 20 days. It was found that the butceptible to the influence of cold. terflies emerging from chrysalids which 6. With different species the degree of had been from 1 to 9 hours old were corntemperature required to produce the most decided change varies. I have succeeded best with Phyciodes tharos at 40 F. [4.4 C.]. At 32 F. [0 C.] have destroyed many Grapta chrysalids but this may have, been principally because the chrysalis was too tender when exposed. REVIEWS. pletely changed; some which had been from 30 to 60 minutes old were not changed while others of same lot were greatly suffused. I concluded that with this species it was not necessary that cold should be applied after the chrysalids had llardened in order to change the form. [PRO ESSOR EDUARD BR_IID: S interest- the nervous system in more than fifty speing papers upon the nervous system of in- cies. Up to the time of appearance of sects which appeared during 1878 and [Professor Brandt s papers but little had 1879 [see Rec. nos ] in the been published upon this subject; for ex- Hore Societatis Entomologicae Rossicae ample, the metamorphoses of the nervous are valuable additions to the literature of system had been traced in only eight spethe subject. The amount of research upon cies (ibur lepidoptera and four coleoptera). which the author s conclusions are based, Many important facts were ascertained in can be best understood perhaps by con- his studies and the papers published both sidering that [Professor Brandt examined in German and in Russian and fully ilthe nervous system of nearly a thousand lustrated with photolithographic plates prespecies of adult insects and of about one sent the facts in a systematic and carefully hundred and twenty-five species of larvae condensed form. G.D. and that he studied the metamorphoses of

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