TRANSACTIONS OF NORTHERN ILL. HORTICULTURAL SOCIETV. 315 



Birds seem to be the natural antagonists of such insects as are exposed 

 to view, or which are but slightly concealed, whilst those which are 

 deeply hidden in the trunks of trees, in fruits, in the earth, or in the 

 water, for the most part escape them. But it is important to bear in 

 mind that what may be called exposed insects, embraces not only the 

 superficial larva:, such as the leaf-eating and the leaf-rolling caterpillars, 

 but it includes almost all kinds of insects in their perfect or winged state. 

 The crops of small birds are often found to contain fragments of the hard 

 wing covers and legs of beetles. Those birds which sjjend most of their 

 time on the wing, like the night-hawks, must depend almost wholly upon 

 winged insects for subsistence. Swallows are often seen skimming over 

 the surface of ponds in search for the newly emerged aquatic Neuroptera. 

 And the fly-catchers capture most of their prey upon the wing. On the 

 contrary, we know that insects in their perfect or imago state are rarely 

 attacked by either predaceous or parasitic insects. They are either too 

 hard to be injured by them, or too active to be caught by them. It is 

 therefore in their larva state that insects are so extensively destroyed by 

 the predaceous and parasitic species of their own class. But like all gene- 

 ral rules this has its exceptions. A few of the larger and more active 

 carnivorous insects, such as the dragon-flies, capture their i)rey on the 

 wing, in a manner very similar to that of the fly-catching birds. A few 

 cases, also, are on record of the parasitic ichneumon-flies being known 

 to emerge from the bodies of mature beetles. (Westwood, II, pp. 142-3.) 

 But these instances are so rare that it is reasonable to suppose that the 

 parasites did not attack the adult insects, but that they dejiosited their 

 eggs in the bodies of their larvre, but at so late a period that they did not 

 corjie to maturity till after their foster-parents had i)assed through their 

 transformations. 



But this exemption of imagos from parasites does not seem to include 

 those outside of the hymenopterous order. The larvii; of the parasitic 

 beetles, (Meloc, Sitaris, Ripiphorus, and S/y/ops,) are found in the bodies 

 of adult bees and wasps ; and many of the two-winged Tachina; are known 

 to deposit their eggs upon the bodies of beetles. Many persons are fami- 

 liar with the eggs of these flies on the backs of jiOtato beetles. 



Mr. Geo. M. Dodge, of Bureau county, wrote to me in 1872 : " More 

 than half of tlie Colorado potato beetles tiiat I have found on our jjotatoes 

 this fall have had the eggs of some kind of Tachina on their wing covers, 

 sometimes as many as seven or eight on one beetle." Mr. Dodge also 

 found similar eggs on the Ly/fa inari^inaia, one of the blistering beetles 

 which are injurious to potatoes. A European author, Leon Dufour, has 

 described a species of Tachina which he reared from the larva slate, and 

 which he found in one of the Tortoise beetles; and another which he 

 reared from one of the bugs pro])er, Pentatonta y^Hsca. And Dr. .Shimer, 

 of Mount Carroll, has obtained a small species of the same family from 

 the striped cucumber beetle, Diabrotica vittata. But these coleopterous 

 and dipterous jjarasites, though considerably mnnerous in the aggregate, 

 are relatively small in numbers when compared witii the almost countless 

 hosts of hymenopterous parasites, the Ichneumonida.-, the Chalcidida:, and 



