A STUDY IN HYPERPARASITISM 3 
species over the period before small brown-tail moth larvae are again 
available is apparently the chief bar to unlimited multiplication. 
There are always many disturbing factors that modify results for 
a particular period or in certain localities, making it necessary to 
view these relationships in a broad way, as they occur in the long 
run, in order to acquire a clear understanding of them. 
Just as there are many conditions and agencies that operate to 
check the undue increase of primary parasites, so, too, there are 
numerous factors preventing the excessive increase of hyperpara- 
sites. Some of the more important of these are: The lack of sufficient 
hosts in available situations, because of previous excessive parasitism 
or destruction by other means; the habit of the adults of most species 
of feeding at the puncture holes made by the ovipositor, and so ren- 
dering many parasitic hosts unfit for sustaiming hyperparasitic 
larvae; competition among hyperparasites for the same host; tertiary 
parasitism; enemies such as rodents, birds, and predacious insects 
that destroy both the primary parasite and the hyperparasite feeding 
upon it; climatic factors, etc. All these and many other factors 
combine to maintain, in the long run, the proper relation between 
hyperparasites and primary parasites. 
SYSTEMATIC POSITION OF HYPERPARASITES 
By far the greater number of the insect hyperparasites are Hymen- 
optera belonging to the so-called parasitoid groups, and particularly 
to the Ichneumonoidea and the Chalcidoidea. In the Ichneumo- 
noidea they are found chiefly in the subfamily Cryptinae, and in the 
tribe Mesochorini of the subfamily Ophioninae, both of which con- 
tain many species of very considerable importance as hyperparasites. 
Very few, if any, members of the true Braconidae are hyperpara- 
sitic, although some species of the Alysiidae, which may properly be 
considered as constituting a subfamily of the Braconidae, have this 
habit. It is among the Chalcidoidea that hyperparasites are most 
abundant. Numerous species in the Callimomidae, Chalcididae, 
Kurytomidae, Microgasteridae, Eupelmidae, Encyrtidae, Pteromali- 
dae, Elasmidae, and Eulophidae have been observed to be hyperpara- 
sitic; and some such species may also be found in the Cleony- 
midae when the habits of this group are better understood. 
The Cynipoidea and the Serphoidea also contain forms of known 
hyperparasitic habits; and with further studies upon the biology of 
members of these superfamilies, more instances of such parasitism 
will probably come to notice. 
There are apparently few true hyperparasites among the Diptera, 
despite the abundant occurence of the parasitic habit in this order. 
But certain Bombyliidae, like (Hemipenthes) Villa morio L. and 
Anthrax velutina Meig., according to Baer (/), occasionally prove 
very destructive in Europe as parasites of Tachinidae that are im- 
portant primary parasites of injurious forest insects. Davis (7) has 
also recorded the bombyliids Exoprosopa pueblensis Jaenn., E. 
fascupenms Say, and Anthrax parvicornis Coq. as hyperparasites. 
They were reared from cocoons of certain species of Tiphia that are 
parasitic on white grubs, Phyllophaga spp. A very few species of 
Coleoptera have been found to be hyperparasitic, at least under some 
conditions. The more interesting of such records are those by 
