October, '08] JOURNAL OP ECONOMIC ENTOMOLOGY 317 



Margaropus annulatus Say, in which the oviposition period is shown 

 to range from eight days in summer to forty-two days in winter. 



2. Relative rapidity of development. A host which passed through 

 its developmental period more rapidly than any of its parasites has 

 the greatest chance for safety, and conversely, the parasite with the 

 most ra[)id development must be considered first in a scheme of para- 

 site utilization. The development of the boll weevil may be best 

 illustrated l)y a curve which shows 38 days from oviposition in April 

 as necessary before maturity, 13 days in July, and 30 days in October. 

 The development of Bracon mellitor Say beginning in June takes 

 about 25 days, in July and August 10-18 days, in late October 175 

 days. A similar curve may be plotted for each of the five other 

 important species. 



Among one-generation weevils, Lixus musculns Say may be con- 

 trasted with Desmoris scapaUs Lee. The former completes its devel- 

 opment in the fall and hibernates as an adult, but its principal para- 

 site, Glyptomorpha rugator Say seldom matures until the following 

 spring. The Desmoris takes about ten months to develop, and yet 

 it is parasitized by Bracon mellitor, which develops in mid-summer in 

 15 days, and is hence capable of breeding several generations at the 

 expense of the more retarded individuals of the Desmoris. 



3. Relative rapidity in sequence of generations. An instance of 

 greater rapidity in sequence of generations in parasite than in host 

 has just been cited. In the case of the boll weevil and most of its 

 parasites a rapid sequence of generations takes place, but at prac- 

 tically the same rate. There is a notable exception in the cases of 

 the two species of Pediculoides, which attack the weevil. These spe- 

 cies reproduce at the rate of a new generation every foiir days. If 

 other factors did not interfere, the mites could become very efficient 

 enemies of the boll weevil. 



4. Retardation of development. It is very common among insects 

 for some individuals to develop more slowly than others of the same 

 age. There are many causes for this phenomenon, among which may 

 be classed the character of the food supply. The boll weevil breeds 

 both in squares and bolls, but the development in the latter is much 

 more retarded than in the former. If a cold spell finds immature 

 stages of the boll weevil in dry bolls, the development may be retarded 

 and prolonged until the following spring, but if the individuals are 

 in squares at this time, they will more than likely mature under the 

 heat of the sunshine in the succeeding warm spell and hibernate as 

 adults. 



When the parasite species has a short period of activity, this char- 



