68 Annals Entomological Society of America [Vol. V, 
certain of our identification we have sent specimens to Dr. 
Marchal for comparison. In a letter of February 9, 1912, Dr. 
Marchal informs us that our specimens are identical with 
Linnodytes gerriphagus. 
Caraphractus cinctus Walker. 
— 
On December 7, 1911, we collected some aquatic plants 
(Ludvigia palustris) from a small pond at Ithaca, in the stems 
of which we found an abundant supply of the eggs of one of the 
back swimmers (Notonecta). Over half of these eggs contained 
larve of a Hymenopterous parasite in which could be observed 
the legs and antennz of the developing pupe. Four to five 
larve were found in each egg. The heads of all did not point in 
the same direction. Plant stems containing a supply of these 
eggs were kept in aquaria in a warm room and on December 19, 
some young back-swimmers had hatched and were swimming 
actively about. Adults of the parasite had also emerged and 
were observed to be actively swimming in the water. One of the 
parasitized eggs was removed from the stem and placed under 
the microscope. It contained four adults, one of which, a male, 
was beginning to gnaw a hole in the end of the egg shell. This 
male emerged within five minutes, and taking a position on the 
top of the egg shell stripped off the pupal sheath from antennez 
and legs. This one was followed by a second male and two 
females, all emerging within nine minutes through the same 
opening. 
The adults of this species seem perfectly at home under 
water and swim quite rapidly by means of their wings with a 
jerky motion, corresponding to the wing strokes made at the 
rate of about two per second. The legs are trailed behind and 
are not used in swimming. They spend much of their time 
walking nervously over the stems of submerged plants, the 
surface-of which they examine carefully with the tips of their 
antenne, as if searching for eggs in which to oviposit. They are 
able to walk on the sides of the glass aquaria and on the under 
side of the surface film. After transferring a jar of water con- 
taining these parasites from one building to another a number 
were found on the upper side of the surface film in the air and flew 
across the surface trailing their legs attached to the film. They 
emerge from the water by crawling up some object and forcing 
their way through the surface film. (Fig. 2.) 
