BIOLOGY OF LIMNEEIUM VALIDUM. '73 



number of caterpillars, a small, flat tray was used, wire screened 

 on the bottom and covered with glass. A small hole in the side of 

 the tray was found useful in introducing fresh foliage sprayed 

 with sweetened water, as food for the caterpillars and parasites. 

 In the first experiments several females of the Lminerifim were 

 confined with a limited number of caterpillars, but later, when it 

 was discovered how readily the parasites attacked the hosts, the 

 number of the latter was proportionately increased. Dissection of 

 the caterpillars was chiefly relied upon in working out the results 

 of each experiment. 



BEHAVn^R OF LIMNERIUM VALIDUM (cRESSOn) IN CONFINEMENT. 



This species did not become overrestless in confinement, and hardly 

 betrayed the excitement that some parasites are said to do when 

 in proximity to their hosts. This tranquility may possibly be ex- 

 plained by the fact that the Limnerium was always confined with 

 species of caterpillars that do not naturally serve it as hosts, and it 

 might have been stimulated, perhaps, to greater activity by fall 

 webworms. The females, however, readily oviposited in 4 of the 6 

 species of caterpillars with which they were confined. The postero- 

 dorsal part of the host was usually chosen as the most suitable point 

 for attack, and there seems to be a more or less well-developed instinct 

 in this as well as other parasites to keep away from the head of the 

 caterpillar in ovipositing. This instinct is not so necessary for large, 

 strong parasites like Limnerium validum^ but may be of great ad- 

 vantage to small, weak species like 2Ietcorus or ApanteJes. These 

 frequently attack cateri)illars that are many times their size, and 

 might easily fall a victim to one vicious sweep of the host's head, or 

 become so daubed up by juices exuding from the mouth of the ex- 

 cited caterpillar that they could not escape. As circumstantial 

 evidence of the existence of this instinct, comparatively few eggs were 

 found near the head in dissected caterpillars, and by far the greater 

 number was found in the posterior half of the body. A favored site 

 for them was in the extreme tip of the postero-dorsal part of the body 

 cavity just beneath the integument. 



The males of Limnerium were slightly more active than the females 

 in running about the cage, but they paid no attention to the caterpil- 

 lars, and but little attention to the females. None was ever seen 

 attempting to mate. 



LIMNERIUM VALIDUIM AS A PARASITE OF EUPROCTIS CIIRYSORRHCEA 



( LINNAEUS). 



Three experiments were undertaken during February and ISIarch, 

 1910, to determine whether Limnerium validiini would successfully 

 attack brown-tail caterpillars, and to collect data, if possible, on the 

 earlv stages. 



