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strong to be controlled by those parasites wliifh. donbtless. formerly held them 

 within bounds ; but even among these, were the partial checks removed, we 

 should very soon feel their loss, and, perhaps, better appreciate their value. 



The term parasite, as used in this country, is of a somewhat general 

 meaning. Thus, the louse is a true parasite because it lives and has its home 

 upon the body of its host, and while extracting its nourishment therefrom 

 does not necessarily destroy life. The bee moth, Gallcria cereana. Fab., 

 although it may cause the death of an entire colony of bees, is not a parasite 

 at all, but simply a mess-mate. It does not devour the bees, but simply robs 

 them of their store of food. 



Our beneficial insects are of neither one of these two clas.ses, because they 

 not only feed upon the body of their host, but cause its death thereby ; for 

 this reason, that class of Insects, which In this paper are termed parasites, 

 are, by most foreign naturalists, designated as cannibals, wliich is really the 

 more proper term. All beneficial insects are not necessarily cannibals, how- 

 ever, the scavenger beetles being a notable exception, while on the other hand, 

 the cannibals are not all of them beneficial, as some of them destroy those 

 which are directly engaged in preying upon the in.iurious species. 



Of the beneficial cannibals we have two classes. First, such as deposit 

 their eggs in or upon the body of their victim, the young hatching therefrom, 

 feeding upon the living tissue. Second, such as catch and devour their prey, 

 or extract the juices from it, rejecting the more solid portions of the body. 

 The first of these classes is composed almost entirely of insects belonging to 

 either one or the other of the two orders, Hymciwptcra, the most numerous, 

 and having four transparent wings, and Diptera. or flies, which have but two 

 wings. The second class is made up of a vast multitude of insects, belonging 

 to all orders. Some of these are cannibals in the larval or worm stage only, 

 others during all of their stages of develoiiment. 



The parasitic Hi/menoptcra, which so largely compo.se the first class, 

 nearly all belong to one or the other of the three families. Ichneumon flies, 

 Icliiiciiiiioui(l(r. egg parasites, Proctotnrpidcp and the Clialcididw. The first 

 are described as being readily recognised by the usually long and slender body, 

 the long, exserted ovipositor, which is often very long and protected by a 

 sheath formed by four stjiets, of the same length as the true ovipositor, 

 Tlialessa linwtor. so called on account of the crescent-like spots across the 

 body, is a good Illustration of one portion of this family. With the aid of her 

 long ovipositor, the female is able to probe the burrows of wood-boring larvfe 

 and deposit her eggs in their bodies. Pimpla pcdalis, Cr^-ss., and P. coth 

 qiiisitor. Say., are both parasitic on the tent caterpillar, while P. aiiiuiUpcs, 

 Br., commonly called the ring-legged pimpla, is parasitic on the larvie of the 

 codlin moth. Two other allied species. Biacon chants, Riley, and Labciia 

 f/ratlator, Say., destroy the flat-headed apple tree borer. Another, a Braconid, 

 Microdiis carinoides. Cress., attacks the apple-bud worm, iJcco;).sis malana, Fid. 

 Two other species, 8if/alphiis curciilioni.s. Fitch, and Tliersilochus conotraclieli, 

 Riley, attack the larvEE of the plum curculio. The former during one season, 

 in the vicinity of St. Louis, Missouri, was found by Dr. Riley to have destroyed 

 three-fourths of the early developed larvoe of this pest. The long-tailed 



