THE TEEEAPIlSr SCALE. 63 



PREDACEOUS ENEMIES. 



At Mont Alto, Pa., in 1912, the lacewing fly ChrysojJa nigricornis 

 Burm. made an attack during the twigward migration which was mi- 

 important, although it continued until the larvae migrated to the 

 twigs. This species was reported in 1893 by Mary E. Murtfeldt as 

 actively attacking the larvae of this lecanium. 



Larvae of Hemerohius stigmaterus Fitch were present in 1912 in 

 considerable numbers and the result of their attack was quite notice- 

 able. 



The predaceous pyralid Laetilia coccidivora Comst. was present in 

 1913, and its larvae made a very vigorous attack. The eggs were 

 placed singly among the scales upon infested twigs, apparently during 

 the first half of June, and hatched in about 6 days. The larva is 

 greenish black, with a black, slightly bilobed head, and feeds within 

 a delicate silken tube which it constructs from scale to scale as it ad- 

 vances along the twig. It first attacks the gravid females, and 

 hundreds of their empty derms can often be seen clinging to one 

 another and to the silken tubes upon trees where it has fed. When 

 the larva reaches its fuU development it spms a cocoon within the 

 silken tube, usually near the axil of a bud or at the base of a fruit 

 spur. L. coccidivora, at Midvale, Pa., requires about 10 days to pass 

 through the pupal stage. The imagos emerged from their cocoons 

 during August and deposited their eggs upon the twigs among the 

 young scales, which were at that time migratmg to the twigs. The 

 larvae of this second brood made a vigorous attack upon the young 

 females. This predator is aggressive and under favorable conditions 

 can undoubtedly control this scale. The author observed its work 

 during the season of 1913, in the orchard of Mr. A. Newcomer, near 

 Midvale, Pa. It was, however, heavily parasitized, and so made 

 very little impression upon its host. Two species of parasites were 

 reared in abundance from this pyralid at Midvale, Pa. They were 

 Mesostenus thoracicus Cress, and an undescribed species of Habro- 

 bracon. 



The predatory bug CamptohrocJiis nebulosus Uhl., although not 

 found at Mont Alto, Pa., was reported by Mary E. Murtfeldt as prey- 

 ing upon the active larvae of this lecanium at Kirkwood, Mo., in 1893. 



Species of CoccineUidae of the genus Hyperaspis are undoubtedly the 

 most efiicient agents in the control of this lecanium. Miss Murtfeldt, 

 in reporting upon Hyperaspis signata for 1893, says: ''The flocoulent 

 larvae of this coccinellid were very numerous and active among 

 swarming larvae of L. nigrofasciatum but were not found upon any 

 other coccid or aphis during the season." 



Mr. A. B. Gahan, in Maryland Agricultural Experiment Station 

 Bulletin 149, mentions the attack by ladybirds and says: ''* * * 

 the species most commonly observed being the twice-stabbed lady- 



