Feb. 2. 1920 Life History of Eubiomyia calosomae 485 



The eggs are almost fully developed at the period of deposition, and 

 hatch ordinarily in less than 24 hours. In two instances, one on July 

 31 and the other on August i, the eggs were deposited and hatched 

 within 3 hours or less. This is the shortest time recorded. On August 

 5, 1917, an instance was noted where an ^gg was deposited, hatched, 

 and the larva had entered its host in less than 13 hours. On August 5 

 at 9.30 a. m. one egg was observed on a beetle and was removed from 

 its host 24 hours later, still unhatched. 



The embryo during hatching makes its way out of the chorion through 

 a small hole (Pi. 58, A) made in the thin membrane on the ventral side. 

 This exit hole is near the anterior end of the egg, the extremity at which 

 the larva emerges from beneath. Fertile eggs in any stage of develop- 

 ment if removed from the exoskeleton of the beetles always fail to hatch. 

 This results probably from the immediate drying of the membrane when 

 exposed to the air or the lack of the exoskeleton of the beetle as a base 

 for the embryo to press against in forcing an exit. 



LARVA 



FIRST INSTAR 



One larva less than a day old, dissected from a beetle, measured 2 mm. long and 0.82 

 mm. broad. Another larva 2 days old measured 2.5 mm. long and i mm. broad. 

 Color white. Form elongate, broadest across eighth and ninth segments, tapering 

 gradually towards anterior end. The segments are provided with irregular annular 

 rows of minute black spines which are very indistinct in this stage. Young larva in- 

 closed in a thin, white, membranous encasement or funnel, formed apparently by the 

 growth from the injured or punctiu-ed tracheal branch to which it is attached . Funnel 

 soon changes to brown upon exposure to light. 



The small larvae enter their host immediately after hatching, probably 

 through the spiracles. A dissection, August 5 at 2 p. m., of an adult 

 Calosoma sycophanta which contained one egg of Eubiomyia calosomae 

 deposited in late afternoon or early evening of August 4 revealed a small 

 maggot inclosed in a "funnel" attached to the tracheae in the region of 

 the metathorax. The anal stigmata of 1±e larva protruded into a 

 hole forced through the wall of the tracheal branch. The spiracles of C. 

 sycophanta are composed of an elongate chitinous ring, the inner margin 

 of which is thickly clothed with short hairs directed towards the center. 

 The spiracles measure from 0.8 to 0.9 mm. long and 0.3 to 0.37 mm. 

 broad. In a laboratory experiment, an egg of E. calosomae was easily 

 forced into the aperture made by pressing the spiracle open. This leads to 

 the supposition that the young larva enters in this way. Some other lab- 

 oratory experiments were tried which also tend to strengthen this point. 

 Several partly developed third-instar larvae were transferred from a 

 parasitized beetle to a normal living specimen. This was accomplished 

 by making an incision in the dorsum of the abdomen of the second 

 beetle and inserting the larva, the wound soon healing. The body of a 



