( cxxi ) 



for the reason why herbivorous insects are not much more 

 numerous than they are. We must turn to some other de- 

 structive influence of a kind constantly operating, in other 

 words, to their active enemies, and with reference to this 

 influence, I plead for all practicable additions to the informa- 

 tion that we possess. 



Destruction hy active enemies. 

 I have enumerated in a note some of their chief enemies, 

 which are of a most varied description, attacking them in all 

 stages.* The elaborate contrivances for protection of Lepido- 

 ptera in all stages are in themselves more than suggestive of 

 the extent to which they suffer, or have in the past suffered, 

 from enemies ; but much observation is wanted if we ai-e really 

 to know instead of to conjecture the means by which the 

 destruction is effected. Examination of the crops, castings 

 and stomachs of birds and other insectivorous animalsf afford 

 valuable help in this direction. A scrutiny of the rejected 

 wings, often found in plenty beneath the habitual resting- 

 places of birds, often leads to useful results. Evidences of the 

 amount of protection afforded by nauseousness or irritating 

 hairs is accumulating, but there is room for much inquiry as 

 to the actual operation of the horns, erectile tentacles, and 

 apparatus for ejecting offensive or corrosive fluids with which 

 so many larvae are provided, especially whether and to what 

 extent these drive off or frighten away those terribly destructive 

 foes, the ichneumon flies and the parasitic diptera.| 



* Enemies. In imago stage : ' Birds, especially in tropical and semi- 

 tropical countries, lizards, night-jars, owls, bats, spiders, dragon-flies, 

 mantids, ants, wasps, carnivorous beetles (see Mr. Floersheim's careful 

 description of the great extent to which beetles attack and kill sleeping 

 butterflies, Tutt, Ent. Record, vol. xviii (1906), pp. 36-9). In pupal 

 stage : Besides many of the enemies of the imago, mice and shrews, some 

 ichneumon flies, especially while the pupte are soft ; pupa diggers are 

 recorded as finding many more pupse in October or November than in 

 late autumn or winter. In larval stage, in addition to many of those 

 above specified, the vast tribe of parasites, liymenopterous and dipterous, 

 and bugs. In the egg stage, birds, ants, spiders, predaceous insects (Mr. 

 Floersheim finds many eggs of P. machaon and other Papilios sucked 

 dry by a small bug. Ent. Proc. 1906). 



t Such as those made by Mr. Guy Marshall, Trans, Ent. Soc. Lond. 

 for 1902, p. 348 et scq. 



t Scudder, as cited by "Wallace ("Darwinism," p. 238), thinks nine-tenths 

 of the North American butterflies are killed by parasites before they reach 

 maturity. 



