588 



those in New Brunswick in 1912 and 1919. Individual outbreaks 

 appear to be due to the landing of a flight of moths, infestations 

 always appearing suddenly rather than rising gradually. 



The life-history, habits and behaviour of the parasites concerned in 

 the present studj^ are described in great detail, and unless otherwise 

 stated apply mainly to Fredericton. The Tachinid, Compsilur.a con- 

 cinnata, Meig., has more than one generation a year in New Brunswick, 

 though the exact number is not known. Under favourable conditions 

 about six weeks are required for the completion of a generation. This 

 fly is larviparous and deposits its young in or near the mid-intestine 

 of the larval host. The carcass of the host is entirely consumed 

 before decomposition sets in. Lydella hyphantriae, sp. n., deposits 

 its larvae in the third to last stage larvae of the host in fine weather 

 only. In some localities larviposition began about 13th in others 

 not until 22nd August ; it lasts about two or three weeks. The 

 parasitic Urvae were all found in the mid-intestine of the host, between 

 the peritrophic membrane and the wall proper, this being apparently 

 their normal feeding ground. Ernestia ampeliis, Wlk., hibernates in 

 the pupal stage, the adult flies emerging in the latter part of May or 

 middle of June according to weather conditions. The maggots are 

 deposited from 2-4 weeks later and are dependent for food on a 

 host larva crossing their path ; they ma}^ spend five days on the twig, 

 after which about 26 are spent in the host as larvae. Pupation may 

 last about 270 days ; there is apparently only one generation a year, 

 though under im usually favourable conditions a partial second 

 generation may occur. There is also reason to suppose that the main 

 generation is double-brooded, the early brood attacking July cater- 

 pillars such as Hypliantria. Pupation occurs in the ground. 



Hymenopterous parasites include Campoplex [Ameloctonus) pilosulus, 

 Prov., which lays its eggs in the caudal end of the second, third or 

 fourth stage of the host larva. The larval stage lasts about three 

 weeks, and the host is kept alive until the last possible moment ; 

 when death is about to ensue, the parasite immediately begins the 

 destructive feeding stage. Pupation occurs within a cocoon in the 

 host and lasts about nine days. It is possible that a spring or early 

 summer generation occurs on some host other than Hypliantria, 

 though nothing is known of the activities of this parasite before 

 August. There is apparently only one generation a year of C. {A.) 

 validus, Cress., though in the southern parts of the United States 

 there are two, in which case it is probably a normal parasite of Mala- 

 cosoma americana. It is also a minor parasite of Hemcrocampa leuco- 

 stignia. In its habits and behaviour it is very similar to C. pilosulus. 

 Apanteles hyphantriae, Riley, has so far only been reared from 

 Hyphantria. The eggs are usually deposited during the first two 

 weeks in August, when the larvae of Hyphantria are in the second 

 and third stage. The eggs hatch within about seven days, and the larval 

 stage lasts about two weeks. The pupal stage lasts from 5-6 days, and 

 hibernation occurs in the adult stage. Nothing is known of the 

 activities of this parasite in spring. In Washington, D.C., this species 

 has two generations a year, and there may also be two in New Bruns- 

 wick, in which case the first must attack some host other than 

 Hyphantria. Therion morio, ¥., is a common parasite of H. cunea 

 and has also been recorded from Vanessa cardui, Iphidicles ajax and 

 Zerene centenaria. The eggs are inserted at the caudal end of the 

 larval_host. They probably hatch in from 10 to 14 days. A very long 



