DEVELOPMENT OF THE PAEASITES. 57 



It may therefore be possible that a parasite will visit the same square 

 several times and oviposit. In general it may be said that as the 

 primary parasitism of the boll weevil increases the superparasitism 

 also increases, with the result that sometimes the parasitism might 

 be considerably increased if every egg reached a single host. The 

 following instances will illustrate this. At Calvert, Tex., 41 stages 

 were attacked by 44 parasites, although only 36.5 per cent of the 

 weevils were parasitized. If every parasite egg had reached a host, 

 there would have been 107.3 per cent parasitism. At Dallas, Tex., 

 out of 309 weevil stages, 44.6 per cent were attacked by 216 parasites. 

 The possible parasitism was 69.9 per cent. Many other instances of 

 this kind could be given, but these two cases illustrate the condition 

 perfectly as it exists in many places during the fall of each year. 



The time for oviposition apparently differs for the various species. 

 Microhracon mellitor, as a rule, oviposits before the boll-weevil larva 

 has constructed a cell, that is, several days before the flared square falls 

 or dries. Eurytoma tylodermatis appears to oviposit in squares on the 

 plant after the normal time of falling and hence is more important in 

 hanging dry squares. Catolaccus spp. and Microdontomerus antho- 

 nomi favor fallen forms for oviposition. The chalcids generally 

 oviposit after the weevil larva has formed its cell. Tetrastichus 

 Jiunteri is most frequently found in fallen squares. 



7. THE DEVELOPMENT OF THE PARASITES. 



THE EGGS. 



The eggs of the boll- weevil parasites are all oblong-elliptic and 

 either smooth or sculptured. The eggs of several species have at 

 one or both ends a small tube which is tied into a knot. Six types of 

 eggs of the boll-weevil parasites have been closely observed and 

 designated by number in the records of rearing. These are illus- 

 trated on Plate II. The eggs of all the boll-weevil parasites are 

 placed in the weevil cell or on the larva or pupa and usually without 

 injuring the latter. 



Type I. — Type I is the egg of Cerambycohius cyaniceps. It was 

 determined for the species by the use of a mica plant cage in which 

 the parasite was isolated with newly infested squares. This egg is 

 about 0.8 mm. long, pure white, cylindrical, unsculptured, and with 

 a narrow neck, which is twisted into a knot, probably by the ovi- 

 positor after the latter has released it. (Plate II, fig. 3.) 



Type II. — This is the egg of Microdontomerus anthonomi, as shown 

 by the rearing of an isolated specimen. The color is white, the egg 

 being distinguished by the slightly papillose sculpture and by the 

 nipple at one end. It measures 0.38 mm. in length and 0.11 mm. in 

 breadth. (Plate II, fig. 1.) 



