236 JOURNAL OP ECONOMIC ENTOMOLOGY [Vol. 2 



A MOTH LARVA PREDATORY UPON THE EGGS OF THE 



BAGWORMi 



By A. B. Gahan 



In the course of some rearing experiments of the parasites of the 

 common bagworm, Thyridopteryx ephemercfformis, during the past 

 fall and winter, the writer was surprised on numerous occasions to 

 find in the cages specimens of a small pyralid moth. The repeated 

 occurrence of this handsome little lepidopteron led to an investigation 

 to ascertain the reason for its presence. The result was the inter- 

 esting discovery that the moths, which were identified by Dr. H. G. 

 Dyar as Dicymolomia jidianis WaUv., were feeding in the larval stage 

 upon the eggs of the bagworm. Numerous bags collected in February 

 from cedar and black locust were cut open and in a large percentage 

 of them larva3 in varying stages of development were found buried 

 among the eggs in the old pupal skins of the females. In one instance 

 two larvae were found in the same bag. In every case where a full 

 grown larva was found, the eggs of the bagworm had been completely 

 destroyed. A larva was placed in a small vial with some of the eggs 

 and later observed to seize an egg in its mandibles and devour its 

 contents. When full-grown the larva crawls out of the egg case, and 

 proceeds to spin a small cocoon at the tip or free end of the bag 

 within which it changes to a pupa five-sixteenths of an inch in length 

 and of a clear pale red color. The imago after escaping from the 

 pupal skin forces its way out of the bag at the lower end. Its normal 

 time of issuance can at present be only conjectured, as specimens were 

 obtained in the laboratory in each of the months of January, Feb- 

 ruary, March and April. Under outdoor conditions, they would prob- 

 ably have appeared in late April or early May. 



That this predatory moth constitutes a considerable check on the 

 bagworm in this locality cannot be doubted when it is known that in 

 some cases 25 to 30 per cent of the female bags were infested ; and 

 that its presence in the bags was not a purely accidental or local 

 occurrence, but is a more or less well developed habit if not charac- 

 teristic is proven by the fact that Prof. A. L. Quaintance reared it 

 from the same source in Washington, D. C, coincidentally with the 

 writer (as was brought out in a discussion before the Entomological 

 Society of Washington in March, 1909). 



Dr. Dyar informed us that the normal habit of the species as here- 



^Contribution from the Entomological Laboratory of the Maryland Agi'icul- 

 tural Experiment Station. 



