4, Prolegs, usually two or five pairs os Lepidoptera 
Prolegs, usually six or more pairs—or none 
Hymenoptera, Tenthredinidae 
Prolegs inconspicuous; leaf- or bast-mining forms 5 
5. Circular holes cut in the leaves 
Hymenoptera, Megachilidae 
Leaves rolled into a small, compact bundle 
Coleoptera, Curculionidae 
Grasshoppers associated with injury 
Orthoptera, Acrididae 
Walkingsticks associated with injury 
Orthoptera, Phasmatidae 
C. Twig Pruning and Other Injury 
6. Injured portion hollowed or mined; injury caused by 
larvae or bark beetles, which are usually present ff 
Injury caused by external feeding or ovipositing, which 
removes a portion of the bark or causes a definite 
mechanical injury or a resin-infiltrated scar ........ 13 
Cottony-masses on tips of twigs concealing the insects ; 
conifers: .).= _Homoptera, Coccidae, Phylloxeridae 
7. Injury on two or more whorls of the terminal of conifers; 
inactive, curved larvae under bark or in pupal cells in 
WOOC ew ers | cen sree Coleoptera, Curculionidae 
Twigs or brances of hardwoods or conifers containing 
bark beetles or powder-post beetles or a cylindrical 
shotlike hole, usually darkly stained, directly entering 
injured portion 
Coleoptera, BUR Bostrichidae 
In ysOUuneRWISG 4 eee) es ae 8 
8. Twigs not mined below fading portion .__. 9 
Twigs mined far below fading portion, ‘tunnel often ex- 
tending to the ground ..... Coleoptera, Cerambycidae 
rea ONCE Seater ee ea ene ee LO 
UAC OOGSS mite (tote) ss onal sooth Srey ial 
10. Larvae with prolegs; often pitch masses at point of 
INJURY. = Lepidoptera, Olethreutidae 
Larvae without conspicuous pr olegs; usually a spine on 
lastseement! 2125 26.23. Hymenoptera, Tenthredinidae 
11. Larvae with well-developed prolegs; usually colored; 
usually in more tender parts of twigs 
Lepidoptera, Olethreutidae, Aegeridae, Cossidae 
Larvae with under- peve oped prolegs in pees portions 
OMFtWIGS eS LN ence geome ys 
12. Elongate, flat larvae; ‘mines filled 
Coleoptera, Buprestidae 
Cylindrical larvae; mines open 
Coleoptera, Cerambycidae 
> There seems to be no simple and practical method of separating the leaf 
miners of the four orders that have species with this habit. Those found 
in conifers are probably either Lepidoptera or Hymenoptera; those on 
hardwoods may be Lepidoptera or Hymenoptera, or of the families Curcu- 
lionidae, Chrysomelidae, or Buprestidae of the Coleoptera; or they may 
be Diptera of the families Agromyzidae or Cecidomyiidae. 
33 
