254 Bulletin 133. 



army- worm, and they are the most destructive of its natural 

 enemies. 



Wherever the worms abound or are on the march, they are 

 usually accompanied by two-winged flies (one is shown natural size 

 at a, figure 72), which are often so numerous that their buzzing 

 reminds one of that of a swarm of bees.* These tachina flies are 

 usually the most important and effective of the enemies of the 

 armj'-worm. A careful examination of a hundred worms in 

 almost every army that ravaged crops in our state last 3'^ear would 

 have revealed the fact that from ten to seventy-five, or even more 

 in some cases, of them bore upon their backs near the head small 

 white eggs stuck fast to the skin. At c, figure 72 is shown a 

 caterpillar bearing three of these eggs natural size ; the same eggs 

 are shown enlarged, in position, at d, above c, and another worm 

 bearing seven similar eggs at d below c. As many as eighteen of 

 these eggs have been found on a single army- worm, but five is 

 about the usual number. These eggs are stuck to the caterpillar's 

 skin by the tachina flies which buzz around a worm until a favor- 

 able opportunity occurs when they swoop down and quickly stick 

 on an o-ZZ- Doubtless the eggs are placed near the head to pre- 

 vent the worm from getting at them with its jaws. From these 

 eggs there soon hatches a maggot which bores its way through 

 the caterpillar's skin and then revels in the juices and fatty tissues 

 of the body, gradually sapping the life of the worm. But few of 

 the army-worms which bear these tell-tale marks — the eggs — of 



* Two species of these flies were apparently about equally numerous in 

 infested fields in New York last year. One species, the red tailed tachina 

 fly ( Wintheinia 4-pustulata Fabr.), is shown natural size at a, and nmch 

 enlarged at b in figure 72. It was first described in this countr}' by Kirkpatrick 

 in 1S60, but Mr. D. W. Coquillett has recently stated that it is an European 

 species and was described by Frabricius in the last century. Mr. Coquillett 

 sends us the following synonyms for this insect : Exorista leiicaniae Kirk. ; 

 Senomctopia tnilitaris Walsh ; Exorista cecropice Riley, M. S. ; Tachina 

 deilephila O. S.; Exorista infesta Williston ; Chaetolyga riifonotata Bigot ; 

 Chaetolyga' rnfopida Bigot; Exorista citiata Towusend ; Exorista platy- 

 satnice Townsend ; Exorista datancs Townsend. 



The other species closely resembles the one just discussed and is known as 

 the yellow-tailed tachina fly {Belvosia unifasciata Desv. ). It was first de- 

 scribed as Exorista flavicaiisa by Riley, but Mr. Coquillett has recently 

 found that Riley's type is the same insect as B. unifasciata Desv. 



