SCALE-INSECTS. 21 



may often be found, and it is noticeable that where it abounds the 

 eggs of the Coccid are often shrivelled or empty. It is not im- 

 probable that this Acarus may feed on the eggs. It appears to 

 belong to the genus Tyroglyphus, a mite which is not usually 

 carnivorous ; but Mr. A. Michael, an authority on mites, seems 

 to be uncertain whether TyroglypJms may not make a meal of 

 the Coccid.* No others amongst the Diaspidinse appear to be 

 directly attacked, nor any of the Lecanidinae ; but amongst a 

 number of Dactylopius ylaucus on a leaf there may often be seen 

 a miriute caterpillar, apparently covered with many tufts of hair. 

 This is the larva of the common ladybird (Coccinella), a beetle 

 which, in both the larval and perfect states, feeds 011 Aphides, 

 Coccids, and other insects. The larva may sometimes be seen 

 holding a Dactylopius in its powerful jaws and devouring it. 

 Another larva, smooth and without hairs, performs the same 

 functions it is the young of a small dipterous fly, apparently 

 one of the Syrphida, insects also predatory ; but this seems to 

 be rare. In America, similar larvae are said to feed upon the 

 " black scale " (Lecanium olece) . In this country, as far as is 

 yet known, Lecanidic are not directly attacked by the lady- 

 birds. 



But this direct warfare by other animals is of small conse- 

 quence. A more important check on the increase of many 

 Coccids is afforded by the indirect action of minute hymeno- 

 pterous insects, which make use of them as receptacles for their 

 eggs. This plan is adopted by several Hymenoptcra, of the 

 families Chalcididie, Ichiieumonidte, Proctotrupidae, &c. They 

 do not devour their prey ; they allow it to live that they may 

 live on it. By means of their long ovipositor they pierce its 

 body, and deposit in it an egg. As the victim grows the egg 

 matures, changes into a larva, and still remains in the body of the 

 Coccid ; changes again into a pupa, and by this time the Coccid 

 is at liberty to die, for the parasite has no further use for it ex- 

 cept as a shelter ; then, when the proper time arrives, the perfect 

 fly emerges and departs. All Coccids are by no means equally 

 subject to this system. In the United States, according to Mr. 

 L. O. HoAvard,t parasites are found in nearly all genera 

 Diaspidiiiae, Lecanidinse, or Coccidinae. In this country, as far 

 as observation shows at present, the LccaiiidinsE are the most 



* Quart. Journ. Royal Micros. Soc., Feb., 1885. 

 t Report of the Entomologist, U.S. Dep. of Agric., 1880, pp. 350-371. 



