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and the length of the tube of the corolla. 

 Several of our species of Bomhus must 

 be able to do efficient work in their 

 cross-pollination, as the measurements 

 of their tongues indicate. Mr. Robert- 

 son, who has kindly identifled the in- 

 sects I sent him, gives me the follow- 

 ing measurements : 



The tongue of a female of Bombus 

 scparnlKf: measured 11 mm., while that 

 at B. Pcint^tlh-aiilriis was 16 mm. long. 

 1 frequently saw a large species of 

 BombuK, probably B. Pennsi/lvankict, 

 which entered the flowers in a normal 

 way, and most of the flowers were pol- 

 linated by this insect. Besides this 

 there was one other humble-bee, a 

 worker of B. v<i(j(in!<{?), which visited 

 the flowers, but mostly those which had 

 previously been used by B. Pcimrii/l- 

 ranicm. The tongue of this insect 

 measured 6.5 mm., so that it was hardly 

 long enough to reach the nectar, and I 

 doubt whether the insect is strong 

 enough to push the upper lip back ; as it 

 regularly visited the older flowers, no 

 doubt it may be of service to the plant. 

 AnUiophora and 3Icli><sodes, which 

 have longer tongues than those of 

 Bnmhuit Penn.tyhunicus, are frequent 

 visitors to flowers with deep seated 

 nectar, but they were not noticed on 

 Phloinis; on the Other hand Xytocopa 

 Vii-ghiica made perforations and used 

 them exclusively. 



The two species of PMomin are much 

 alike in the awn-pointed lobes of the 

 calyx, the hinged arrangement in the 

 upper lip, and the compactness of the 

 flower- cluster. The flowers of Ph. Biit:- 

 !<diunH are somewhat larger, and are 

 therefore adapted only to long-tongued 

 insects, since the tube of the corolla is 

 22-22 mm. long. But the tube of Ph. 

 iuherona is only 10 mm. long, so that it 

 is adapted to a much larger range of 

 insects. Accordingly Loew found Ph. 

 JJif.s-.sc^iVma visited in the Berlin JJotanic 

 Garden only by Bombus hortontm, and 

 he says that Anfhophnra piUpes is the 

 only other insect in North Germany 

 which can do adequate service in its 

 pollination. 



In both of these species there is a 

 beautiful contrivance for securing 

 cross-pollination. But while the Syrian, 

 according to Loew, is proof against 

 such depredators as Bombus tcrrcstris, 

 which perforates many European 

 flowers in order to get at their nectar, 

 Ph. tub(^rof<a is not proof against these 

 urlwelcomed visitors. Notwithstand- 

 ing that Xijloaqxt. has a tongue of 7-5 

 mm., and can therefore get at a portion 

 of the nectar in a normal way, it 

 chooses rather to perforate the flowers, 

 the awn-pointed calyx lobes ofl'ering no 

 resistance. 



Tlic Colors or Flower Species. 



But I think the most striking differ- 

 ence between the species is in color, 

 and as this is such an interesting bio- 

 logical fact, I will summarize what 

 Hermann MuUer says about it in his 

 classical work " Die Befruchtung der 

 Alpenblumen :'' 



Not only have Ilymeiinptera been mo8t active in 

 tiie fievelopiiient ol eucli pef.ullar contrivances as 

 tlie boll-shiiped corollas ot Onnvallarias, Campanu- 

 las, and Gentians ; the funnel-shaped corollas of 

 Rhododendrons and Echiums ; tlie tubular corollas 

 of Loniieras; the closed corollas ot Ijinarias and 

 Antirrhinunis ; the spurred flowers of AquileKias 

 and Aconiiums : tlie labiate flowers of Laiuluuis, 



Palvias, Melampyrum, and Pedicularis ; the in- 

 verted flowers with small openintrs of Arctostapby- 

 loHaiul Vaccinium : and the papilionaceous flowers 

 of 'I'rifolium and llubiaia ;— but they have also in- 

 fluenced the colors ot flowers in a most raarlied 

 detiree. Flowers adapted to a large ranwe of in- 

 sects, like those of CoinposilcE, Saxijragtw, Valeri- 

 anacetc, PotentiUa, and Rtnimculus, are usually 

 yellow or white. But in such highly luoditied 

 flowers as Lamiums, Salvias, Delphiniums, Aconi- 

 tums. and Aquilegias, the colors are generally 

 violet, blue, pink, or purple. In these and other 

 genera a change seems to have stepped in, especi- 

 ally where flowers have the same structure and are 

 pollinated by the same class of insects. 



Our species of Ifonarda show this 



color-range beautifully In Labiates 



the prevailing colors are blue, rose, 

 lilac, and purple ; seldom yellow or 

 white. Ldriiimn album, hovxixr, is 

 white, while L. muculutum is red. 

 Plilomis tuberosa is purple. Ph. Ru.s- 

 sdkoia is yellow. Sah-ia ylulimmi is 

 yellow, S.pi-dtin.m blue. Why should 

 we have changes in color of such 

 closely related species ? 



Slight changes in color must there- 

 fore be of great use to an insect, just 

 as changes in color of parts of a flower 

 after pollination are of use to the insect 

 by indicating that its services are no 

 longer needed. Muller believes that 

 the changes in color, in closely allied 

 species, have been produced for reasons 

 of this kind. 



The Perforation of Floivers. 



The perforation of flowers by insects, 

 and in a few cases by birds, to get at 

 the nectar by fraudulent means, is a 

 matter of cotnmon observation ; but in 

 a few cases this is the normal way of 

 procedure, as has been shown by Dar- 

 win and Muller, for insects are obliged 

 to perforate the lax inner membrane of 

 some orchids (nearly all of the British 

 Ophrete according to Darwin) in order 

 to get the nectar which lies within 

 their tissues ; and in the case of Labur- 

 num, etc., Muller has shown that in- 

 sects puncture the thickened bases of 

 the standard petal in order to get nec- 

 tar. I ought also to call attention to 

 the destructive work of species of 

 J/((y«c7u7e, which cut out parts of the 

 petals of roses, pelargoniums, etc., and 

 use them to line their nests. 



A century ago, Sprengel notice'd that 

 flowers were perforated. Since his time 

 many European as well as American 

 observers have noticed perforations. 

 Among them I may mention Darwin, 

 Delpino, Ogle, Kerner, Loew, and Her- 

 mann Muller. To Loew, and especially 

 Muller, are we greatly indebted for 

 painstaking labor in giving lists of 

 flowers and their visitors, and, with the 

 exception of these and a few by other 

 investigators, we have no statistical 

 tables on the pollination of flowers and 

 their insect visitors, so that we have 

 little accurate information as to what 

 insects perforate flowers. 



It is of value to know not only that a 

 given flower is perforated, but also 

 what relation the insect bears to the 

 flower which it perforates. It is, in- 

 deed, interesting to follow out these 

 relations from Muller's tables 



Darwin, in his " Cross and Self-Fer- 

 tilization," etc., states that out of many 

 hundred specimens of red clover ex- 

 amined by him, nearly all were per- 

 forated, and he has even seen whole 

 Helds in the same condition. Thos. 

 Belt and others have noticed the same 

 thing. It is quite as common for red 



clover to be perforated in this country 

 as it is in Europe 



Italian Bees and the Red Clover. 



In the summer of 1883, in the vicinity 

 of La Crosse, Wis., I noticed large 

 numbers of honey-bees on the flowers 

 of red clover, aiid wondered whether 

 they made perforations, or what they 

 were doing. In some cases they ob- 

 tained pollen, but in a vast majority of 

 cases nectar was collected through per- 

 forations made by some other insect. 

 Among bee-keepers there is a notion 

 that the Italian bee is able to get nec- 

 tar from red clover. I doubt whether 

 this is true, for in my experience I 

 never found them collecting nectar in 

 the normal way ; they seemed to collect 

 only through perforations made by 

 some other insect. 



One thing will show, in part at least, 

 why honey-bees go to the red clover at 

 certain times and not on other occa- 

 sions. It is a well-known fact that the 

 amount of nectar secreted by a plant 

 varies according to season and locality. 

 There are periods, as I have had occa- 

 sion repeatedly to observe, when hive- 

 bees cannot collect enough to supply 

 their young, and they then freely use 

 the perforations made by Bomhus and 

 other insects ; but when there is an 

 abundance of nectar they pass over 

 fields of red clover, and when 2fonanla 

 punrAata is in flower, and has a good 

 supply of nectar, they will pass over 

 fields of white clover, and fly some dis- 

 tance to fields of wild bergamot. 



Although the rule seems to be that 

 honey-bees do not perforate flowers, 

 there seems to be exceptions, for no 

 less an authority than Hermann Muller 

 states that they perforate the flowers 

 of Erka Mmlij\ using their mandibles 

 to bite holes in the tube of the corolla. 

 The tongue of the honey-bee is only 

 6mm. long, so that it is not able to get 

 the nectar otherwise in these early 

 flowers. Later he found honey-bees 

 collecting nectar in the normal way, 

 but he failed to observe whether these 



late flowers were smaller or not 



It is not always an easy matter to 

 tell whether an insect makes the per- 

 forations, especially when these are in 

 the form of longitudinal slits, or 

 whether it is merely looking for the 

 perforations of some other insect. In 

 flowers where the tissue is firm, these 

 slits close over quite effectively, and 

 are not readily seen. While the honey- 

 bee makes, at most, few perforations, 

 Muller records many cases in which it 

 uses perforations made by other in- 

 sects; butit is suQicient here to refer 

 to his works for these. 



In this country, Meehan believes that 

 the honey-bee perforates the flowers of 

 Salvia Splendens. Delpino, Comes, 

 and a few other observers, also state 

 that the honey-bee perforates corollas. 

 I think, however, that generally honey- 

 bees only use the perforations made by 

 other insects, and they are certainly 

 quick to perceive these perforations. 

 Muller records the most interesting 

 case of Salvia Solarea, in which the 

 tube of the corolla is so long that the 

 honey-bee is not able to get the nectar 

 in a iiormal way. It made several at- 

 tempts, but did not try to perforate 

 the corollas. When, finally, it found 



