84 ENTOMOLOGICAL SOCIETY OF ONTARIO. 



degree, a beetle, Chcetocnema parcepunctata, also very common on clover and other plants' 

 Curiously enough, where I find the former in greatest abundance, there are almost none 

 at all of the beetles, while in a clover held not over one-fourth of a mile away, the be 

 ar<^ very abundant and none at all of Halticus bractatu* Tint we have here a well 

 defined case of simulation can hardly be doubted, yet the simulating form and the form 

 simulated avoid each others company as if mortal enemies, there being no other forms 

 present that at all resemble them. 



I have made no experiments with any of these insects in order to determine whether 

 or not they are distasteful, for the reason that any results obtained with the facilities at hand 

 would have added to instead of reducing the complication. I might, like Professor Pla- 

 teau, have eaten some of these insects, and learned whether or not they were distasteful 

 to me, or I might have fed them to domestic fowls, or wild birds in confinement, but failed 

 entirely of securing the data required. It seams to me that the only testimony in these 

 matters, worthy of consideration, is to be found in the stomachs of insectivorous birds, 

 and other vertebrate enemies it any, shot while feeding in the exact locality and under 

 perfectly free and natural conditions. Giving a bird perfect freedom and allowing it to 

 make its own selections and discoveries is one thing, while confining it, and doing these 

 things for it, is quite another. It is what these natural enemies actually do, under per- 

 fectly natural conditions, that we must learn, and not what they can be induced to do.* 



Over a large portion of the United States, and to a less extent in Canada, primitive 

 conditions no longer obtiin, while modern conditions are undergoing a constant change } 

 the plow and axe of the husbandman having exterminated many forms, both vertebrate 

 and invertebrate, if not entirely, over lirge tracts of country, and we may and probibly 

 do have cases of peculiar coloration and movements that were once protective, but now 

 remain only as vestiges of a former state of affairs, the forces that brought them into 

 existence no longer existing, except locally. 



One phase in the radical changing of the natural flora and fauna over areas of greater 

 or less extent, whereby both plants and insects are entirely displaced by others, emphati- 

 cally different, is shown by the two accompanying illustrations, showing the bed of a small 

 lake just prior to and after being brought under cultivation, and an aquatic insect fauna 

 d : splayed by another, terrestrial, and more or less connected with th3 introduced fljra. 

 (See plate preceding, page 65). 



In Northern Illinois a species of willow, Salix discolor, the leaves of which are 

 nearly white on the under side, grows in wet places, on hummocks, and to the height of 

 from one to six feet, forming a regular compact cluster. The foliage is fed upon by a 

 hard, heavy bodied beetle, an inch or more in length, and often nearly a half inch across 

 the shoulders, in color ebony black with white pubescence, which on the elytra is arranged 

 in irregular transverse fascia?, with more or less parallel markings, all of which combine 

 to give the insect the appearance of a white surface, irregularly tessellated with black. 

 This beetle, Plectrodera scalator, fig82 feeds by eating holes in the leaves, or irregular notches, 

 leaving the mid and lateral veins, with irregular borders of the 

 leaf along these nearly intact. The beetle remains on the under 

 side of the leaf, the eaten portions of which, against the background 

 formed by the interior of the thicket, appear black, while the 

 uneaten portions appear nearly white. In this way a beetle sta- 

 tioned on an uneaten leaf has almost the exact appearance of a leaf 

 partly eaten, and so perfect is the deception that a fairly good 

 collector may pass some years in a locality where the species is very 

 common, without seeing a single specimen, until he detects the 

 deception. Aside from its considerable dimensions and hard body, 

 this beetle is armed with a rather formidable spine on each side of 

 Fig 82. the thorax, thus rendering it rather an undesirable sort of prey for 



any of the smaller birds, and altogether too much so for any invertebrate enemies. In 



* I may be permitted to state that, in Ohio, birds cannot be shot for the purpose of making scientific 

 investigations, without ruuning the risk of being arrested and heavily fined therefor. 



