HOST RELATIONS OF COMPSILURA CONCINNATA 19 



Heterocampa guttwitta Walk, and Heterocampa umbrata Walk, 

 pass the winter as pupa?. The former is periodic in abundance, the 

 latter never so. It is, in fact, rather rare, only a few specimens 

 reaching the laboratory during the entire period in which collections 

 were made. The food plants of both are chiefly maple and beech. 

 Neither of the species is nearly so favorable as the Datanas. 



Melalopha inclusa Hiibn. is a tent-making species and hibernates 

 as a pupa. The species feeds on willow and poplar and has been re- 

 ceived in abundance during the last three years. Frontina frenchii, 

 Eulimnerium validum Cress., and Apanteles sarrothripae Weed 

 seem to be its chief parasites. The species has given Compsilura 

 several times but it can not be considered highly as a host. 



Pheosia rimosa Pack, is solitary; its food plants are willow and 

 poplar. It is uncommon and only during the last year have there 

 been received any good-sized collections. It has about the same status 

 as the species of Heterocampa. 



Larvae of the red-humped caterpillar (Schizura concinna S. and 

 A.) are found in the field from July to October. This species hiber- 

 nates in the prepupal stage under leaves and rubbish. Its food plants 

 are varied, apple, birch, willow, and bayberry being much favored. 

 It is common in many localities and is one of the insects most con- 

 stantly received. It is at times much favored by Compsilura as a 

 summer host, but is of little consequence as a winter one. It has on 

 one occasion, however, given Compsilura in the spring. 



In Schizura concinna, Compsilura meets with considerable com- 

 petition from Winthemia quadripustulata, Phorocera claripennis, 

 Phorocera erecta, and Gymnophthalma americana Town. The last 

 named, however, attacks the larvse in an earlier stage than the rest, 

 and its growth is so far advanced by the time the host larva is 

 attacked by the others that it probably has no trouble in maturing. 

 At any rate, a very good percentage of parasitism is maintained 

 each year by G. americana. A summary of the tachinid parasites 

 shows that the combined efforts of the native species (G. americana 

 excepted) are less effective than that of the exotic. Such may not 

 always be the case, however, for in its relationship to this host Comp- 

 silura is most variable. Certain years have given but a negligible 

 amount of parasitism, whereas others have given a parasitism as 

 high as the most favorable host. The principal hymenopterous para- 

 sites seem to be Hyposoter fugitivus Say and Eulimnerium validum 

 Cress. These species attack the host in the second and third stages, 

 the former usually issuing from the fourth and fifth stages and the 

 latter from the cocoons. 



Schizura unicornis S. and A. is apparently a solitary species and 

 has always been received in small numbers, usually during Septem- 

 ber. The larvse feed upon a great variety of food plants. There is 

 but one record of rearing Compsilura from it and that was from a 

 full-grown larva collected in the fall, the parasite issuing the follow- 

 ing spring. 



Gerura occidentalis Lint, also appears to be solitary and the col- 

 lections of it are always small. The larvse are found chiefly on wil- 

 low and poplar. Compsilura has been reared only once, the adult 

 issuing during August from a larva collected in July. 



