some British Guiana Hymenoptera. 315 



colour, and of a papery consistency, easily broken. Pupa- 

 tion lasts a little over a week, and the adult wasp then bites 

 its way out through the mud wall of the nest, leaving a 

 neat circular hole. The small green metallic bee, Euglossa 

 cordata, L., often utilises these disused cells for its nest. 

 A fungus occasionally destroys the stored spiders and 

 finally the young larvae. No actual parasite of the species 

 has ])een observed up to the present. It appears, however, 

 that only about 60 % of the stored cells produce an adult 

 wasp. 



S. jigulus, Dahlb. Closely allied to the above species, 

 and with similar habits and distribution, though not so 

 numerous. 



Genus Sphex, L. 



S. ichneumoneifs, L. A common and widely distributed 

 species throughout the Colony. For its subterranean nests 

 it usually chooses a dry piece of soil, often in the centre 

 of a path or other places where people are frequently 

 passing. While constructing the initial excavation for its 

 nest it is a most conspicuous object, moving rapidly about 

 on the surface of the soil. The following observations 

 made by Mr. C. B. Williams are of interest. " In this 

 instance the insect was boring into soft pegass soil on 

 swampy land at the foot of a hill. High spring tides 

 from the river invariably cover the land. The burrow 

 was commenced about 1.40 p.m., and at 1.45 p.m. it was 

 about I inch deep. At 2.19 the wasp entered the hole 

 backwards, remaining below a few minutes, and then 

 came out again. Burrowing continued till 4 p.m. These 

 nests are stored with four or five short-winged grass- 

 hoppers, either nymphs or brachypterous species ; the 

 nest is not closed up between the insertion of each 

 grasshopper." 



Sphex {Isodon(ia) costipennis. Spin. Issororo, N.W.D. 



S. (Harpactopiis) thmnae, F. An uncommon species 

 which does not occur on the coast lands. Constructs 

 burrows in soil and stores them with a single grasshopper, 

 which is placed head first in the nest. The egg is attached 

 at the base of the grasshopper's hind-leg (C. B. Williams). 



Genus Podium, F. 



P. denticidahnn, Sm. An uncommon though widely 

 distributed species. 



