194 JOHN D. TOTHILL. 



Predators. 



Birds. As the scales grow larger a few probably become the prey of birds. In 

 summer however other insect food is much more easily available. Forbush mentions 

 cedar birds, chickadees, and the white-breasted nuthatch as at least occasionally 

 feeding on this scale ; and Slingerland and Crosby add the brown creeper to this 

 list. Concerning the part played by birds in the control of scale-insects in general, 

 Jarvis says (I.e.) " It is highly probable that these insectivorous birds rank first in 

 the control of the larger kinds of scale-insects, such as Eulecanium, Coccus, and 

 Kermes." He suggests that the part played by birds in the control of smaller scales 

 is rather inconsiderable. 



Insects. Predaceous insects undoubtedly take a levy of the growing scales. 

 Dr. Howard in " The Insect Book " remarks that " While the lice are young and before 

 they have formed a protective scale they are avidly destroyed by the larvae of the 

 syrphus flies, of the lace-wing flies, and by certain small predatory bugs. The most 

 efficient of their natural enemies however are probably the ladybirds." Slingerland 

 and Crosby say (I.e.) " Some of the ladybird beetles, the twice-stabbed especially, 

 devour many " of these sea es. In Canada it seems that the part played by predaceous 

 insects in the control of the pest is quite a minor one. 



Mites. Mites, and more especially Hemisarcoptes (fig. 2), take a certain levy from 

 the growing scales. In a letter to the editor of the Canadian Entomologist Riley 

 in 1878 says " The Dermaleichus figured in my . . . Report feeds upon the eggs of 

 Mytilaspis pomicorticis, as well as upon the insect proper under the scale ; " the 

 mite referred to is probably Hemisarcoptes. Lignieres (I.e.) evidently watched 

 these mites feeding upon young oyster-shell scales. Saunders in his " Insects Injurious 

 to Fruits " says " A species of mite . . . preys on the louse (oyster-shell) as well 

 as on its eggs."* Banks (U.S. Report, no. 108) says of this mite " It feeds on the 

 eggs or on the scale." Ewing and Webster (I.e. p. 126) found one of these mites 

 with its beak imbedded in an adult scale. 



Through the summer of 1917 A. B. Baird made a series of observations at Moncton 

 and found that although the mites did not feed to any great extent on the young scales 

 yet they fed greedily upon the large ones. In one case five hundred scales were 

 examined under a binocular and Baird found 85 per cent to 90 per cent, killed by 

 Hemisarcoptes. The usual condition was to find in these scales one large mite and 

 ten to fifteen little ones all in the anterior end of the scale. 



My own observations, confined to examinations of material collected during the 

 past fall and winter, have shown many instances in which females had died, and not 

 from overcrowding, before eggs had been deposited. The explanation suggests 

 itself that these scales had been attacked in June and early July by the mite. 



* Dearness in 1901 reports this mite feeding on San Jose scale in Ontario. He says 

 " Last year (1899) I received a package of twigs, mostly San Jos4 from Mr. John Gordon, 

 Guilds P.O., Kent County, on some of which there were . . . mites preying on the well- 

 grown female. ... On some specimens received this year from the same neighbourhood 

 these mites were very numerous ... as many as eighteen larval mites were observed 

 under one large scale." 



