430 ENTOMOLOGICAL SOCIETY 



sisting Prof. John Gamgee in his studies of this disease, in Texas, 

 I was strongly impressed with the popular belief that the ticks 

 had some connection with this disease, and, although the idea 

 was at the time scouted by veterinarian authority, events have 

 proved in this, as in several other similar instances, that the pop 

 ular belief, though at first antagonized by current belief-among 

 scientific men, has in the end been justified. 



If we consider this question of parasitism, however, solely from 

 the standpoint of the farmer and stock-raiser, it becomes at once 

 apparent that the injury done by the external forms to domes 

 tic animals is trifling as compared with the immense benefit de 

 rived from the more typical insect parasitism on other plant-feed 

 ing insects. Thus it is difficult to estimate the benefit which 

 agriculture derives from the work of the Hymenopterous para 

 sites. Many a threatened outbreak of some injurious species has 

 been prevented by the sudden multiplication of some of the tiny 

 Chalcidids, notwithstanding their beneficial work is lessened by a 

 number of hyper-parasites which follow them. Even among the 

 microscopic egg parasites, it is well known that one species fre 

 quently destroys nearly every egg of the Cotton Worm (Aletia 

 xylina) in the Southern States over a large extent of terri 

 tory. The Tachinidae are omnipresent, and one can only realize 

 the important part they play in checking injurious species when 

 witnessing the effect of, for instance, the Red-tailed Tachinid 

 (JVemorea leucanice}^ which is a specific enemy of the Army 

 Worm. In fields fairly black with the worms, these flies will be 

 seen hovering about in such numbers that their buzz can be heard 

 for some distance, and sometimes the closest search for hours 

 fails to reveal a single worm which does not carry the white eggs 

 of the parasite. It is chiefly through the agency of this particu 

 lar fly that the Army Worm rarely occurs in injurious numbers 

 for two consecutive years. 



There is, moi'eover, another important economic phase of this, 

 subject of parasitism, and one which has attracted more attention 

 of late years than ever before because of the success of my efforts 

 in the introduction of Ve'dalia cardinalis into California and 

 the practical stoppage by it of the injury from leery a purchasi. 

 I refer to the encouragement, by assisting their multiplication, of 

 the parasites of injurious insects and the introduction from one 



