47 — 



Tachina - flies. 



\"ery frequently we meet with individual specimens of lo- 

 custs that are more or less -'dumpy" or sluggish in their move- 

 ments. AVhen we capture and open them we find one or two 

 shor t, thick, whitish grubs or maggots in the region just behind 

 the head. These are the young of gray-colored, two-wing- 

 ed flies, which ver\^ much resemble the common house-ily in 

 appearance, though they are usually somewhat larger and 

 more robust. These flies belong" to a very large family of para- 

 sitic insects known as Tiicliiiiidtc, and are found quite general- 

 ly distributed over the earth's surface. 



T*r-- 



Fig'. 13. — Xemoi a acriJinium, niale- 

 (Afttr Conih. 



ínlaraed ■! times. 



At least two distinct species of Tachina-flies are known to 

 attack the locust here in Argentina and the surrounding coun- 

 try. The most important of tliese is the Xeuioni acridioniiu 

 of Weyenburg. 



Generally speaking, these Tachina-flies are the most import- 

 ant insect-enemies of locusts in all countries. At times, from 

 their attacks alone, severe locust-plagues are brought to an 

 end. 



As the writer has not had an opportunity of studying these 

 Tachina-parasites of the locust in this country during the 3'ear. 

 and since several other writers have fully described them, a 

 general account of these insects will be given instead. 



"These Tachina-flies firmlv fasten their eggs ^ \vhich are 



