June, '13] TIMBERLAKE: PARASITES COCCUS HESPERIDUM 299 



of integument. The Coccophagus larva then proceeds to cast its me- 

 conium and pupates within the body of the scale, quite after the manner 

 it has when primary. 



Coccophagus lecanii like many of the Aphelininse is normally par- 

 thenogenetic in reproduction and regularly thelyotokous, producing 

 females generation after generation without the intervention of the 

 male. A curious phenomenon occurs when this species becomes 

 hyperparasitic, as the offspring has been found to belong to the male 

 sex in all cases so far observed. This change in the sex of the offspring 

 takes place not only under artificial conditions in experiments, but 

 also in the case of hosts parasitized under normal field conditions. 

 The exact factor in this sex determination has not been discovered. 

 It apparenth' does not inhere in the usually somewhat smaller amount 

 of food, for in some instances the resulting male is fully as large as 

 the normal-sized female. 



Coccophagus lunulatus Howard 



This species of Coccophagus has more specialized habits than the 

 preceding species and is always a primary parasite. It is, moreover, 

 not as common although well distributed in California. It attacks also 

 immature scales of Lecanium corni Bouche and Saissetia olece (Bern.). 

 The original record of its host relationship which states that it was 

 reared from Chrysomphalus aurantii (Mask.) is undoubtedly incorrect, 

 as its peculiar life-history practically precludes the possibilty of its 

 being a parasite of any Diaspine scale.* As a parasite of Coccus hes- 

 peridum it is partial to scales that are about half-grown or larger, 

 but it very rarely if ever attacks those that have become mature. As 

 many as two or three larvse may successfully develop in the larger 

 hosts. 



Unlike Coccophagus lecanii this species never blackens the hypo- 

 dermal tissue of the host although the black-colored pupa lying just 

 beneath the translucent derm, may temporarily cause a blackened 

 appearance. C. lunulatus also differs markedly from lecanii in always 

 avoiding the vital organs of the host, and in pupating in situ before 

 the host has been entirely consumed and killed. The pupae, in fact, 

 are always found in the still living host, which often survives until 

 after the issuance of the adult. This remarkable habit of the parasite 

 is made possible through the fact that it pupates within the last larval 

 exuvia, which becomes filled with air and acts as a protecting shroud. 

 The meconial discharge, moreover, is not voided at random among 



* See Howard, L. 0., Insect Life, vol. 6, p. 232, 1894, and Quayle, H. J., Bui. 222, 

 Cal. Agr. Exp. Station, p. 136, 1911. 



