W. Nowkll 53 



give a reasonable chance of males and females emerging about the same 

 time. 



The second Scoliid to be described, Campsomeris (Dielis) dor sat a 

 (Fab.), is found in Barbados throughout the year. The wasps occur 

 very abundantly on flowers at frequent and apparently irregular 

 intervals, sometimes both sexes together, sometimes with one or the 

 other greatly preponderating. Their visits to flowers cease shortly after 

 mid-day. The males have a curious habit, so far' observed only in the 

 afternoon, of collecting in large numbers on any convenient piece of 

 vegetation, such as a grass stem or a yam vine, forming an assembly 

 like a swarm of bees. The writer is quite at a loss to account for this 

 habit, which occurs in several other Fossorial wasps met with in the 

 West Indies. 



The sexes are very different In appearance. The male is slender, 

 12-17 mm. in length. The dorsal surface of the abdomen is striped 

 laterally with yellow and black, the ventral surface is blue-black; the 

 second (apparent first) abdominal segment is considerably smaller in 

 circumference than the remainder. A narrow yellow band bordered with 

 black makes an almost complete circle on the dorsum of the thorax at 

 the level of the wing insertions and is repeated behind. The antennae 

 are cylindrical, about 8 mm. long. 



The female is stouter and has a length of 14-24 mm. The colour 

 is a uniform shining black with the exception of a brick-red blotch which 

 covers the dorsal aspect of segments three and four of the abdomen, 

 divided only by a black line at their junction. The wings are of a deep 

 metallic blue. The antennae are about 4*5 mm. long. There is con- 

 siderable greyish pubescence on the thorax, legs, neck and waist, and 

 on the front of the head. 



The notable range in length observable in each sex of both Tiphia 

 and Campsomeris is not a regular variation about a central mean. The 

 larger sizes are more abundant. The tendency seems to be towards 

 the attainment of the maximum for the sex, limited by the nutrition 

 available from the single larva of the host. Attention has not been 

 specially directed to the question as to whether there is any tendency 

 to the selection of large grubs by the laying female, but quite small 

 grubs have occasionally been noticed to be parasitized. Observation 

 has seemed to show, quite definitely in the case of Ligyrus, that in a 

 continuous breeding place small larvae are much less common at any 

 one time than those approaching full size, due presumably to the earlier 

 stages of growth being passed over more rapidly, which, granted the 



