LIBRARY

COLLEGE ENTOMOLOGY
25. " RAPHIDIODEA . Raphidians, Snakcilies, Serpentfiies
26.
27.
" MECOPTERA
" TRICHOPTERA
Scorpionflies
Caddisfiies, Caddises.
Casefiies, Water Moths
Caddiccfiies,
28.
29.
30.
31.
" LEPIDOPTERA.
" COLEOPTERA
" STREPSIPTERA
.. HYMENOPTERA
Moths, Butterflies
Beetles, Weevils
Strepsipteruns, Stylops, Twisted-
-winged Insects
Ants, Bees, Wasps, Gallllics. Sawflies.
32. .. DIPTERA
Horntails. Ichneumuns, Braconids,
Chalcids
Flies, Gnats, Midges, Mosquitoes,
Punkies
33.
0<
SIPHONAPTERA Fleas. Chigof:'s
Numbers of Species of Insects
According to Z. P. Metcalf (Ent. News 51: 219-222, 1940), approximately
1,500,000 species of insects have been described during the period from 1758
to 1940.
KEY TO ORDERS-ADULTS
l. Apterous or with inconspicuous vestigial wings. 2
Fully winged or with ntdimentary wings 25
2. Mouth parts mandibulate or for biting and chewing 3
Mouth parts suctorial or for piercing and sucking. 21
3. Mouth parts retracted within the head and with only the apical portions
visible . 4
Mouth parts free and not retracted within the head . 7
4-. Abdomen composed of six: or fewer segments, with ventral sucker and
caudal springing apparatus. (Springtails.) COLLEMBOLA
Abdomen 10- to 12-segmented, without ventral sucker and caudal
springing apparatus . 5
5. Abdominal segments I to III each with a pair of small ventral styli;
antennre and cerci absent; minute and rare. (Proturans.) . PROTURA
Abdominal segments II to VII each with a pair of small ventral styli;
antenna! and cerci or forceps present . 6
6. Body usually covered with scales; long cerd and a median caudal filament
present. (Bristletails.) . THYSANURA
Body smooth and without scales; cerci or a pair of forceps present;
caudal filament absent. (Campodeids,Iapygids.) . APTERA
7. Head prolonged into a beak. (Scorpionfiies.) . . MECOPTERA
Head normal, not prolonged into a beak. . . . 8
8. Small, soft or tough, crawling and running louse-like insects; prothorax:
small and inconspicuous. 9
Small OJ' large, soft or well sclerotized insects; pro thorax normal 10
9. Antennre with five or fewer segments; ectoparasitic on birds and mammals.
(Biting Bird Lice.) .. .. . MALLOPHAGA
Antennre with more than five segments; phytophagous CORRODENTIA
p. 77
P. 59
p. 65
p. 72
p. 399
p. 193
p.l84