December 1895. ] 



PSYCHE. 



315 



an appreciable distance from the base 

 of radius. This wing also shows the 

 unity at the base of tlie wing of the two 

 main Ijranches of cubitus. 



In the examination of a considerable 

 number of wings from various orders of 

 insects I have noted that anal veins 

 arise from certain tracheal trunks or 

 often apparently from one main trinik 

 which divides at the base of the wing 

 into several or mimv branches or rays ; 

 and that this main anal trunk is distinct 



from the main trunk or trunks which 

 run into the pre-anal area of the wing, 

 and which are the foundations of the 

 principal longitudinal veins of the pre- 

 anal area. In the wing of Hexagenia 

 the veins corresponding to those veins 

 marked '• anal " in figure 4 are supplied 

 with tracheae from one main trunk, 

 the anal area trunk, while the first vein 

 in front of these anal veins (called by 

 me part of cubitus) does not receive a 

 branch from this main anal trunk. 



ON THE NEST AND PARASITES OF PR OS O PIS J'AP/PPOJVS 



CRESSON. 



BY A. DAVIDSON, M. D., LOS ANGELES, CAL. 



This bee and Cei-atina dupla are the 

 most common ones that tunnel in the 

 shoots of the elder and mustard in this 

 locality. The cells are built in stems 

 which the parent herself has hollowed 

 out, and measure on an average 4 lines 

 long, by 2 or 3 wide. Thev aie lined 

 with a thin, transparent layer of silk 

 which is spun by the parent bee, and 

 are filled three-fourths full with the 

 light yellow semi-fluid bee-food. The 

 egg is laid on top of this mass, and the 

 cell is closed by the same silken tissue 

 which, in its turn, forms the base of the 

 succeeding cell. The last of the series, 

 when finished, is further protected by a 

 layer of pith of variable depth. The 

 cells are probably normally built con- 

 tiguously, but a few sometimes have 

 partitions of pith, which may be the 

 work of more than one bee. 



Two broods at least are produced 



annually. Bv splitting the twigs con- 

 taining the cells I was enabled to watch 

 the larvae pass through their various 

 stages, and in a series gathered on 

 May 5 at JSIanzana, in the Antelope 

 Valley, all of which were apparently 

 newly constructed, the food was con- 

 sumed in S days after the hatching of 

 the egg. The larvae at this stage are 

 quite active, and in their restlessness a 

 few of them burst through the lining of 

 the cell on the exposed side and made 

 their escape. During this period of 

 activity they void a small quantity of 

 excrement which, being limited to one 

 end of the cell, simulates an artificial 

 partition between the cells. 



In from four to six days after the 

 food was consumed they passed into 

 the pupa stage, and on June 9th with 

 two exceptions all had taken their 

 flight, the time occupied in passing 



