i go 



FARM FRIENDS AND FARM FOES 



the enemy. But the next species to be studied revealed a 

 still different method of reaching the interior of the host. 



Observations upon the development of the Tachinid eggs 

 indicated the probability that some kinds of these flies would 

 deposit living larvae instead of eggs. Two species were 

 especially studied, and it was found that the flies were fur- 

 nished with " a long curved sheath, into the base of which 

 the ovipositor fits, and which tapers to a microscopically 

 sharp point." By means of this 

 instrument the flies are able to 

 thrust the sheath between the hairs 

 of the caterpillar, cut a hole in the 

 skin, and insert the living larva in- 

 side the body of the victim. From 

 the point of view of the parasite 

 this method has obvious advan- 

 tages : the young larva is placed 

 amid favorable surroundings at once 

 with no danger that it will find itself 

 attached to a molted caterpillar skin. 

 And the interesting fact was brought out that various na- 

 tive flies have a similar sheath and doubtless a similar life 

 history. 



A REMARKABLE LIFE HISTORY 



It is not strange that Dr. Townsend found a species that 

 we may for convenience call the Large-horned Tachina Fly, 

 the " most remarkable as regards startling deviations from 

 the previously known manner of reproduction" in the 

 group. It was at first supposed that these flies would 

 deposit their eggs upon the skins- of caterpillars in the 

 old-fashioned way. To a female fly having this habit, the 

 presence of a good-sized gypsy or brown-tail caterpillar 



TACHINA PARASITE OF 



GYPSY MOTH 



Magnified 



