THE DENIZENS OF AN OLD CHERRY TREE. 11 



of its larval enemy, which do not actually kill it until its cocoon is 

 spun, in which, after making a last meal of their host, they turn 

 to pupae. Those under observation appeared in the perfect state 

 in June, from six to nine flies emerging from one cocoon of their 

 host, while from one cocoon of a larger Crabro — C, cephalotes — 

 we took twenty-seven naked pupae of this parasite. 



Another parasite of Crabro leucostotna is an Ichneumon, 

 Phygadeiion gravipes, of which two females emerged from the 

 burrows in June. The wings of this dark brown fly almost equal 

 in expanse those of its host, and its size indicates that the Crabro 

 cocoon is occupied by only one of its enemy.* Our remaining 

 species of Crab?o have the abdomen banded more or less with 

 black and yellow, and are easily mistaken by the non-entomologist 

 for small wasps, which they resemble, not only in shape and colour, 

 but in the possession of a powerful sting, so that care should be 

 exercised in the examination of living specimens. Like other 

 members of the genus they store their nests with living Diptera, 

 packed together in a state of torpor, and in their general economy 

 they appear to be similar to each other. The first of these 

 {Crabro vagus) is shown enlarged at Fig. 5, PL I., of which thirteen 

 specimens — chiefly males — appeared in June. It may be distin- 

 guished from the thirty British species of the genus by the entirely 

 black third segment of the abdomen. Its cocoon is the same 

 shape, but a trifle smaller, than that of Crabro chrysostomus (Fig. 4, 

 PI. I.), and its brown colour is a shade darker than the cocoon of 

 that species. So far as we have examined the larder remains of 

 this Crabro^ the stored Diptera appear to belong to the genera 

 Musca and Pollenia^ but it may bring home prey of other allied 

 genera, as in an untouched larder of a Crabro, which we inferred 

 was made by C vagus, but which did not produce a Crabro, owing 

 to the failure or non-deposition of the egg, we found two whole 

 male specimens of Musca corvina, and one whole female Stomoxys 

 calcitrans. 



From the burrows of this Crabro a female specimen of Antho- 

 phora furcata (Fig. 6, PI. I.) emerged in June — the only bee met 

 with in the stump. Mr. Saunders, in speaking of this species, 



* We are indebted to Mr. T. R. Billups for his kind identification of the 

 Parasitic Hymenoptera of our stump. 



