THE CHALCIDOID GENUS PEETLAMPUS. 



53 



but accurate counts were kept in only a single instance, in v/hich 35 

 out of a lot of 164 puparia, or 21.4 per cent, were found to be para- 

 sitized by Perilampus. This is known to be above the average, taking 

 the material which was reared or studied as a whole. 



The results of several counts given in Table I are indicative of 

 parasitism in 1909. 



Table I. — Percentage of parasitism of Varichseta hy Perilampus, 1909. 



The variation between the individual lots is due to their having 

 been collected in different localities. Although it may be stated with 

 assurance that the average was much higher than during the previous 

 year, exact comparisons are impossible, since parasitism varies in 

 different nests in the same locality, and in different localities. A 

 long series of careful calculations would be required in order to secure 

 accurate results. 



As might be expected, the cocoons of Limnerium validum were 

 parasitized to an approximately equal extent, and in these cocoons 

 were found a few planidia of another species, wliich has been desig- 

 nated in the notes as ''Species A." The summer-issuing Limnerium 

 and Apanteles were not so heavily parasitized as a rule, probably 

 because many of the planidia did not enter the caterpillars until a 

 part of those afflicted by these parasites had died. 



The percentage of healthy caterpillars of Hyphantria bearing the 

 planidia, either internaUy or externally, ought to be, and apparently 

 is, approximately the same as the percentage of VaricJiseta and 

 Limnerium parasitized. 



SUPERPARASITISM. 



Perilampus versus Perilampus. 



The extent to Avliich Varichseta or Limnerium is parasitized by 

 Perilampus may be easily determined by opening the puparia or 

 cocoons before the planidia have begun to develop, and in this manner 

 the prevalence of superparasitism may be easily calculated. Upon 

 several occasions as many as five planidia have been found upon one 

 host, and four, three, and two are of frequent occurrence. In not a 



