540 NATURAL HISTORY OF ARTHROPODS. 



Megachile centuncularis is one of our most common leaf-cutter bees. It is found 

 through the northern United States and Canada, and all through Europe, as far north 

 as Lapland. A single female of this species, observed by F. W. Putnam, occupied 

 over tvi'enty days in building and provisioning a series of cells under a board. On 

 examination there were found to be thirty cells in nine rovv"S of varying numbers. An 

 estimation of the number of bits of leaf used in the construction of these thirty cells 

 amounted to one thousand at the least. The curious Chalcid parasite, Anthophordbia 

 megachilis, was bred in great numbers from this set of cells. 



The bees of the genus Anthidium do not make burrows for themselves, but make 

 use of those made by other insects. The large holes bored by the larvse of Cossus are 

 often used. The cells are made of down collected from woolly-stemmed plants, mixed 

 with some glutinous matter. The little bees belonging to. Ceratina exca\'ate the pith 

 of brambles. The common Ceratina dupla excavates stems of Syringa, elder, or black- 

 berry, lining her cells with a delicate silky membrane and separating them from one 

 another by mud partitions. This species is parasitized by a very remarkable chalcid of 

 the genus Axima. 



With the sub-family Scopuliijedinse, the hind legs of the females are furnished with 

 a thick coating of hairs which constitute the pollen-brushes. The basal joint of the 

 posterior tarsi generally has its extremity angularly produced. They have no pollen- 

 plates, and the abdomen is destitute of a pollen-brush. The wings usually have three 

 perfect sub-marginal cells, the third antennal joint is often long and clavate, and the 

 mouth is occasionally considerably developed. 



The species of the genus Eucera burrow into the ground. The larvsB remain as 

 such through the wintei-, transforming to pupas in April without sjsinning cocoons. 

 With Anthophora the habits are quite similar, but certain species bore into wood 

 instead of entering the ground. The abnormal chalcid Anthophorabia {Melittobia) 

 is parasitic upon bees of this genus according to Newport. There remains a doubt, 

 however, as to whether or not it is a true primary parasite, as Smith discovered its 

 larvaa feeding upon those of Monodontomerus nitidus, which is a true i^arasite of 

 Atithojjhora. The correct conclusion seems to be that the larvae of both Monodonto- 

 merus and Anthophora are destroyed by this parasite. The bees of the genus Melecta 

 live in the burrows of Anthophora as previously stated. The genus Saropoda seems 

 to connect Anthophora with the next genus, Xylocopa, as its species closely resemble 

 the former in structure, while in habits they approach the latter. They are borers in 

 decaying wood, making longitudinal burrows divided into eight or ten oval chambers, 

 each containing a cell formed of wood scrapings. 



The genus Xylocopa contains the largest species of the genus. They resemble, in 

 general appearance, the common Imrable bees, but are less hairy. These bees bore 

 symmetrical tunnels into solid wood, choosing, in civilized regions, fence posts and 

 boards. The burrow is half an inch in diameter, and runs horizontally across the grain 

 for about the length of the insect's body, when it is turned downwards at right angles 

 and carried to a depth of from twelve to eighteen inches. In boring, the bee is said 

 to progress at the average rate of about half an inch a day, occupying at least two days 

 in digging the first portion against the grain of the wood. The tunnels generally run 

 in opposite directions from the opening, and sometimes other galleries are made, one 

 parallel with the other, using the common opening. It seems certain that the same 

 tunnel is used over and over again, and that a new one is only made when no old one 

 can be found. After the burrow is prepared, the cells are made and supplied with 



