132 INSECTS 



and is resorted to by many insects. This means that 

 when they are disturbed and apprehend danger, the 

 specimens draw in legs and feelers, permit themselves 

 to drop to the ground and remain absolutely quiescent 

 until they believe the danger past. This very habit, 

 however, delivers some of the economically important 

 species into the hands of their arch-enemy man, who 

 spreads a sheet or other catcher beneath a tree or vine, 

 jars the infested plant and gathers in the specimens 

 which on the white background are conspicuous enough, 

 though in sod or on the bare earth they would be 

 well-nigh invisible. 



Warning colors and protective mimicry are other 

 passive defenses. Warning colors are simply bright 

 or contrasting tints that indicate a species unpalatable 

 to ordinary animal feeders on insects of that descrip- 

 tion. That there are such species there is no doubt, 

 for they seem almost entirely safe from predatory foes. 

 Their dress expresses the legend "not good to eat" 

 and so they are left unharmed. Now one type of pro- 

 tective mimicry is found where a species of another 

 group or series normally good to eat so closely re- 

 sembles this unpalatable form as to be readily mis- 

 taken for it, and some of these resemblances are ex- 

 tremely close. Another type is when an inoffensive 

 insect so closely resembles one that is capable of de- 

 fence, that its enemies hesitate to attack. The re- 

 semblance of some Sesiid moths and Conopid flies to 

 wasps is a case in point. In such instances it is quite 

 usual to find that the mimic has some of the same 

 tricks of habit as the protected form and this is at 

 least as powerful a safeguard as the color alone. 



Now what place do these vertebrate enemies hold 

 in the series of checks to insect increase, and how much 

 do they benefit man — the farmer and fruit grower? 



