26 BULLETIN 1487, U. S. DEPARTMENT OF AGRICULTURE 
various species of Meteorus, Rogas, Hyposoter, and Campoplex, 
in a few instances from tachinid puparia, and in one case from the 
mud cells of a psammocharid wasp upon which Dibrachys had been a 
primary parasite. Evidently it is occasionally also a tertiary, having 
been recorded by Ratzeburg (32) as probably parasitic on the hyper- 
parasite Hemiteles socialis Ratz., and having been bred at this lab- 
oratory upon a species of Gelis which had developed upon A. melan- 
oscelus. Because of its wide host range, it can maintain itself in 
large numbers, although one or another of the parasites on which it 
preys be periodically greatly reduced. Accordingly, Dibrachys can 
ate 
Fic. 8.—Dibrachys boucheanus, female 
be obtained in abundance year after year, without noticeable periodic 
recessions. It has proved to be one of the three most serious para- 
sites of A. melanoscelus. — 
Although of small size, it appears to be very hardy, In the lab- 
oratory specimens have been kept alive for two or three months. 
Despite its small size, and contrary to Tothill’s assumption (36), it 
is a prolific species. Under laboratory conditions four females depos- 
ited, respectively, 235, 255, 375, and 389 eggs over a period of approx- 
imately two months. The largest number laid on any one day by 
a single female was 29. It is likely that under natural conditions 
even more eggs may be deposited. Unfertilized females oviposit as 
readily as those that have mated, but the result of such reproduction 
is always males. Nearly always several eggs are placed in the same 
host cocoon, and as many as 14 individuals have been found to mature 
upon a single Apanteles, the species being normally gregarious in 
the larval stage. Females have not been observed to deposit more 
than three eggs at one insertion of the ovipositor, but the same cocoon 
is usually attacked more than once. There is much variation in the 
size of the adults in consequence of the varying number developing 
within a cocoon. The larvae feed externally upon the Apanteles 
larva, like most hyperparasites, and pass through five larval stages, 
ee a 
Se ee ee eee 
\ 
~ 
