The biology in Jamaica of the adults of the sphecid wasp Sceliphron assimile Dahlbom

Abstract. 1. The adult biology of the solitary mud-wasp Sceliphron assimile Dahlbom was studied in Jamaica.
2. Adults were active from sunrise until they finally settled in roosting groups a little before sunset. Nesting took place during an 8.5 h period commencing about 3 h after sunrise but individuals rarely spent > 4 h nesting per day, the remainder being spent in resting and feeding.
3. Males sought females in all places in the habitat.
4. The number of cells per nest was positively correlated to high cell density per unit area but negatively correlated to illuminance.
5. The number of pellets used to build a cell, but not cell length, was negatively correlated to the body length of the builder. There is evidence that females that build multiple nests locate them within a few metres of each other.
6. Incompletely stored cells were closed with an externally concave lamella of mud at the onset of rain or at 16.00—17.00 hours E.S.T. and never reopened the same day.
7. Like other species of Sceliphron studied in this respect S. assimile collected spiders belonging to the Argiopidae (particularly), and also mainly to the Thomisidae, Salticidae and Oxyopidae.
8. The consequences of the nest architecture on mortality and the method of building on distribution are discussed.
9. Protarrhenotoky and proterandry occur and probably influence the sex ratio through differential mortality and fecundity. A suggested interaction between the flight motor and the ovaries could regulate egg production.