Cambridge Entomological Club, 1874

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This is the CEC archive of Psyche through 2000. Psyche is now published by Hindawi Publishing.

Charles Robertson.
Phenology of Inquiline and Nest-making Bees.
Psyche 33(4-5):116-120, 1926.

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[August-Octo ber
Carlinville, Illinois.
Cases observed with a flight of only 1-10 days are excluded as fragmentary.
Comparisons should be made with 6, 105-9. Colletes and Epeolus.-Colletes flies 224 days, Mar. 20-Oct. 30, six together June 20-29 and Aug. 26-Sept. 5. It shows a
maximum of 46.6 per cent June 21, 53.3 per cent flying in July and August. Epeolus flies 148 days, May 29-Oct. 23, four to- gether Aug. 29-Sept. 5. Its flight is 76 days shorter than that of Colletes. C. incequalis lacks only 3 days of completing its flight of 81 days, Mar. 20-May 31, before Epeolus begins. Evi- dently it is not infested by any Epeolus. E. interruptus, May 29-June 19, is evidently an inquiline of C. cestivalis, May 8-July 1. It may, however, belong to C. brevi- cornis, May 29-June 29, or to both.
E. bifasciatus, June 12-Oct.
3, is probably an inquiline of C. latitarsis, June 13-Oct. 1, and perhaps also of C. willistonii, May 28-Sept. 5; E. pusillus, Aug. 26-Oct. 23, of C, americanus, Aug. 18-Oct. 30; E. autumnalis, Aug. 29-Oct. 13, of C. compactus, Aug. 26-Oct. 21. The former pair are small, the latter large. C. armatus, Aug. 17-Oct. 7 may be infested also by E. autumnalis or by E. coreopsis, Aug. 20- Sept. 5.
Grsenicher (3) says Argyroselenis minimus is an inquiline of C. eulophi, which flies 146 days, May 28-Oct. 30. I have taken A. minimus but once, July 8.
Mecaghilini and Cce1ioxys.-The Megachilini, 14 species, fly 165 days, May 11-Oct. 22, all together for 8 days, July 3-10. Six species of Coelioxys fly 161 days, May 12-Oct. 19, all together for 42 days, July 4-Aug. 14.
Megachile brevis, May 15-Oct. 22, may be infested by C. octodentata, May 12-Oct. 19 (I think it has been recorded in Ent. News) and M. mendica,.May 16-Oct. 11, by C. sayi, May 21-Oct. 4. Xanthosarus latimanus, May 28-Oct. 20, is infested by (7. rufitarsis, July 4-Oct. 19, according to Grsenicher (2), and I have


19261 Phenology qf Inquiline and Nest-making Bees 117 seen the inquiline enter the burrows.
Oligotropus campanulas,
June 25-Sept. 14, is probably infested by C. modesta, June 25- Aug. 28, both small species. The flight of C. texana, June 25- Aug. 14, and C. germana, June 25-Sept. 3, are covered by the flight of Megachile generosa, June 11-Sept. 28, M. sexdentata, June 14-Sept. 10, and M. petulans, June 17-Sept. 20. According to Shuckard (7) Coblioxys infests Megachilini with modified front tarsi. There are not as many inquilines as would be expected ot'herwise.
Osmiince and Stelidini-The Osmiinse fly 211 days, Mar. 21- Oct. 18, with a maximum of 75 per cent June 16, 90 per cent flying in June. May 21-25, 28 and June 6-11, 70 per cent are flying. The Stelidini fly 163 days, May 9-Oct. 18, all together May 7-14.
Alcidamea simplex, 85 days, May 3-July 26, and Microstelis lateralis, 43 days, May 9-June 20, are host and inquiline (Crawford 8, 5)., Neotrypetes carinatus, 144 days, May 28-Oct. 18, and productus, 138 days, June 3-Oct. 28, the females mixed and counted for both species, are evidentJy infested by Stelidium trypetinum, 135 days, June 6-Oct. 18. In 6, 109, productus should be ca,rinatus.
Bombince and Psithyrus.-Bombus americanorum, Mar. 5- Nov., and P. uariabilis, Apr. 28-Nov., are host and inquiline, as stated by Frison (1). Their time and frequency indicate this. Halictidce, Sphecodini and Para1ictus.-The Halictidse, Mar. 17-Nov., are probably infested by Sphecodini, Mar. 31-Nov. Chloralictus is probably host of Paralictus, both March 15-Nov. P. cephalicus, May 9-Oct. 19, was taken at a bank where C. zephyrus, Mar. 21-Nov., was nesting.
I would arrange the Halictidse as follows: Halictinse, wing veins not enfeebled; Halictini : Halictus, etc. ; Sphecodini : Sphe- codes, etc.; Lasioglossinse, outer veins enfeebled; Lasioglossini: Curtisapis, Evylaeus; Chloralictini: Chloralictus, Dialictus, Pa- ralictus. The last is an offshoot from Chloralictus. The Spheco- dini were derived from Halictini, not from the forms with outer veins enfeebled.
Andrenidce and Nomadid@.-The Andrenidae fly 227 days, March 17-Oct. 30, have a maximum of 68.8 per cent May 11-13,


118 Psyche [August-Octo ber
75.5 per cent flying in May, 64.4 in April, 48.8 in June. Only
one is flying July 30-Aug. 12, while 6 are simultaneous Sept. 8-20. The Nonadidse fly 212 days, Mar. 21-Oct. 19. Twenty species fly 129 days, Mar. 27-July 27. The maximum is May 5 when there are 14 species flying simultaneously. Three species fly 54 days, Aug.27-Oct. 19, all together for 25 days, Sept. 8-Oct. 2. Forty-five species of Andrenidse and 20 of Nomadidse com- plete their flight before August and are evidently related as host arid inquiline, but there are so many that it is hard to match them. I think Centrias erigerontis, June 17-21, is an inquiline of Pterandrena rudbeckice, June 10-Aug. 17. C. americanus, Apr. 29 -July 16, ends when only 3 Andrenidse are flying, Pterandrena rud- beckice, Trachandrena quintilis and T. obscura. It begins 42 days before any of these, in which time it evidently infests some other species.
Cephen texanus, July 17-27, probably belongs to Trachan- drena quintilis, July 8-29, T. obscura- July 16, or Pterandrena rudbeckice, which are the only Andrenidse flying at the time. Holonomada vincta, Aug. 27-Oct. 2, is probably an inquiline of Pterandrena helianthi, Aug. 27-Oct. 10. H. placida, a small spe- cies, Sept. 6-Oct. 19, may belong to Pterandrena solidaqinis, Aug. 13-Oct. 22, or Andrena nubecula, Aug. 13-Oct. 30. Nomada vicina, Sept. 8-Oct. 19, is most closely associated in time with Pterandrena asteris, Sept. 8-Oct. 21.
Panurgidce and Pasititid@.-Holcopasites illinoensis, June 6- Aug. 23, is probably an inquiline of Calliopsis andreniformis, May 30-Oct. 14. Heterosarus parvus and Pseudopanurgus albi- tarsis are the only other Panurgidse flying in the early part of June.
Anthophoridce and Melectidce.-Five species of Anthophoridse fly 166 days, Apr. 8-Sept. 20, averaging 63.4 days. Excluding Emphoropsis floridana, the male observed for 16 days, the average is 75.2.
Bombomelecta thoracica, April 18-May 28, flies during the time of A nthophora ursina, April 8-June 22. Melecta interrupta, taken twice, June 18, July 19, is rob ably an inquiline of Ame- gilla walshii, July 6-Sept. 20. It no doubt flies much later than Anthemoessa abrupta, May 7-July 29, and Clisoden termimlis, May 25-July 27.


19261 Phenology of Inquiline and Nest-making Bees 119 Emphoridce, Euceridce and Triepeo1us.-The Euceridse fly 198 days, Apr. 8-Oct. 22.
Excluding Tetralonia, they fly 132
days, June 13-Oct. 22. Triepeolus flies 118 days, June 26-Oct. 21, all together for 5 days, Aug. 30-Sept. 3. In 4, 37, I accepted Ashmead's erroneous opinion because Triepeolus was mixed with Epeolus. There were too many of them and they were too large to be inquilines of Colletes. Triepeolus donatus, Aug. 11-Oct. 11 infests Melitoma taurea, June 24-Oct. 7 (Ashmead in 5). T. helianthi, Aug. 11-Oct. 3, infests Melissodes trinodis, June 14-Oct. 6 (Grsenicher 2). T. pectoralis, Aug. 30-Oct. 21, coincides pretty well with M. autum- nalis Aug. 21-Oct. 22. Triepeolus is too late to infest Tetralonia. Tetralonia dilecta, Apr. 18-July 14, may be infested by Holono- mada superba, Apr. 20-June 24.
Of 296 local species, the short-tongued bees are 50.6 per cent. In general they are the primitive bees and occupy the original positions. The long-tongued bees, developed later, have turned to flowers whose nectar has become so deeply seated as to be rather inaccessible to the short-tongues. They have not dis- placed the lower bees, but have taken up new ecological positions. That the long-tongues have been compelled to find new places for themselves is shown in the development of inquilines, 77.7 per cent of which are long-tongues.
Inquilines are 38.3 per cent of
long-tongued bees and 10.6 per cent of short-tongued bees. Of theshort-tongues, the Halictidi~ are the only ones which have developed inquilines, Sphecodini and Paralictus. Natural selection seems to have favored the development of inquilines, just as if they could live at the expense of previously established bees better than they could actively compete with them. About the only adaptive characters shown by inquilines are differences in size. They run smaller than their hosts and the small species belong to small hosts.
The characters by which the species may be distinguished are unusually non-adaptive. The mutationists, with whom the origin of species seems to be the same as the origin of specific characters, might readily point to inquilines as species with whose origin natural selection had nothing to do. The inquilines, however, generally, if not always, have


120 Psyche [August-October
different hosts with which their size and flight are correlated. Natural selection clearly favors this diversification. My view is that the inquilines separated first and got their specific differences afterwards.
An inquiline producing mutants infesting the same host could not produce more individuals and could not become the basis of new evolution any more than one which did not produce them.
As regards species in general I hold that everyone has selec- tive characteristics, holds its own bionomic position, and is the result of natural selection.
Note on Sphecodini.-According to Schuckard (7, 108), St. Fargeau, Westwood and Latreille regarded these bees as inqui- lines, while Kirby and Smith regarded them as nest-makers. Mueller (9, 50) says they feed tjheir young with the disgorged surplus of their own food.
Prison, T. H.
1916. Note on the habits of Psithyrus varia- bilis. Bull. Brook. Ent. Soc. 11: 46-7.
Grsenicher, S. 1905. Some observations on the life history and habits of parasitic bees. Bull. Wis. N. H. Soc. 3: 153-67.
. . . . . . . . , 1906. A contribution to our knowledge of the visual memory of bees. Bull. Wis. N. H. Soc. 4: 138-9. Robertson, C. 1899. On the flower visits of oligotropic bees. Flowers and insects XIX. Bot.. Gaz. 26: 27-37. . . . . . . . . , 1899. Flower visits of oligotropic bees. Bot. Gaz.
28: 215.
. . . . . . . . , 1924. Phenology of anthophilous insects. Flower visits of insects 11. Psyche 31: 93-111. Shuckard, W. E. 1866. British bees.
Swenk, M. F. 1914. Studies of North American bees. University Studies. Lincoln Nebr. 14 : 1-36. Mueller, H. 1883. Fertilisation of flowers.


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