850 Journal of Agricultural Research vol. vi, No. 22 



EFFECT OF PARASITISM ON HOST 



Beyond possibly a temporary inactive condition induced by the sting, 

 the oviposition by the parasite does not seem to injure the host. But 

 shortly after the newly hatched larva begins to feed, the character of the 

 body contents shows a considerable change. The adipose tissue loses its 

 flocculent character and becomes a more homogeneous, more fluid mass, 

 diluted by the blood. This same change in the host was noted by Tim- 

 berlake (9) in his studies of Limnerium validum Cresson. 



Parasitized larvae at the time they leave the fruit are, as a rule, much 

 smaller than healthy larvae, although parasites have been found in 

 hosts of nearly normal size. Whether this smaller size is due to the 

 failure of the host to grow normally or to its failure to pass through all 

 of its stages is a question which has not been determined. 



OVIPOSITION 



In oviposition the female parasite, having found a curculio oviposi- 

 tion scar, raises her abdomen, at the same time releasing the ovipositor 

 from its sheath and, directing it forward between her legs, thrusts it 

 into the tunnel made by the curculio larva. If she can reach the larva, 

 she pierces its skin and deposits within it a single egg. The act of 

 oviposition is very brief, the longest observed having required about 

 two minutes. 



The female T. conotracheli has been observed repeatedly in the cages 

 to attempt oviposition or rather to probe for possible hosts in abrasions 

 of any sort in the skin of the plums provided. This apparently indicates 

 that she can not recognize infallibly the typical scar made by the curculio 

 in oviposition. 



INCUBATION PERIOD 



No exact data on the incubation period are available, but that it is 

 very short is indicated by the fact that in the many young larvae exam- 

 ined in the course of the observations only one egg was found within a 

 host, although they are very easily discovered. At the same time 

 that the above-mentioned egg was discovered, another curculio larva, 

 which had not traversed more than half an inch within the fruit, was 

 found to contain a very young parasite larva. This also would indicate 

 a short incubation period. A curculio larva exposed in a cage for one 

 day, July 1-2, 191 5, to the attack of T. conotracheli and dissected on 

 July 7 was found to contain a very young larva of the parasite. This 

 would indicate a maximum incubation period of six days, although it 

 may have been even shorter than that. 



