252 TRANS. ST. LOUIS ACAD. SCIFNCE. 



adaptation or disharmony must develop among flowers and in- 

 sects of a given region w^henever some plants begin to develop 

 tubular flowers which surpass in length the tongues of their former 

 visitors. In other words, perforations are made by short-tongued 

 humble-bees and Apis, in consequence of the lengthening of the 

 tubes of certain bee-flowers beyond the mean length of the tongues 

 of these insects. For this reason few of the native plantsof Ger- 

 many have nectaries over 17-20 mm. long. If they had, these 

 flowers, being more frequently perforated, would stand less chance 

 of being pollinated than now, and the species might in some cases 

 even become extinct. 



The Carpenter Bees, belonging to the Genus Xylocopa,* do con- 

 siderable injury to flowers in more southern latitudes, where they 

 abound. Delpino, Comes, and others, find that XyJoeopa viola- 

 cea, a native of Southern Europe, perforates many flowers, such 

 as Antirrhinum majus, Linaria vulgaris, and Mirabilis Jalapa. 

 JTylocopa Virginica, according to Cresson,t is found in the mid- 

 dle, southern, and western States, and of the 27 species of this 

 genus mentioned in his catalogue this is the most northern, and 

 has the widest distribution. The species no doubt causes con- 

 siderable annoyance, as Mann, Ryder, and Miss Murtdfeldt have 

 shown. Mr. Mann was the first to describe one method which 

 it uses to perforate flowers, in which "the insect applies its sharp 

 and wedge-shaped maxillse to the grooved surface of the tube and 

 splits this open 3 or 4 mm. from the base." Dr. Schneck and Mr. 

 Van Ingen each record several cases — Physostegia, Mertensia, and 

 Petujiia — in which the tube of the corolla had longitudinal slits, 

 but as perforators they found humble-bees {^Bomhusf). As these 

 slits correspond so well to the slits I found on the tube of the. co- 

 rolla of Phlomis, I bring them up in this connection. I fre- 

 quently found this Xylocopa in the act of making longitudinal 

 slits in the tube of the corolla of Phlomis tuberosa. The insect ap- 

 plies its powerful mandibles against the tube of the corolla until 

 it gains entrance, then, thrusting its maxillae in as far as it can 



• Xylocopa differ from Bombus in that the mouth-parts are adapted to boring as well as 

 sucking. They are capable of boring a foot or more into pine and even hard wood, and in 

 constructing their nests show considerable architectural skill. 



t " Catalogue of N. Am. Apidce, with Description of New Species." from Trans, of the 

 Am. Entomological Society, vol. vii. ' 



