CHARLES ROBERTSON 179 
sonii ¢, denticulata ¢ 9, illinoensis ¢ 9, fq, sayi ¢ 9, ab, Xan- 
thidium luteoloides ¢. 
Short-tongued Bees (12)—Halict. (2): Augochlora viridula, 
Chloralictus caeruleus fq, zephyrus fq, Evylaeus arcuatus, foxii fq, 
Halictus lerouxii, Odontalictus, Paralictus platyparius; Andren.: 
Andrena mandibularis 4, pruni ¢ 2, fq, Opandrena dubia ¢, fq, 
Trachandrena hippotes <. 
Diptera (15)—Syrph.; Eristalis dimidiatus, Helophilus similis, 
Orthoneura nitida, Sphaerophoria, Syrphus americanus, Xantho- 
gramma felix; Conop.: Myopa vesiculosa; T'achin.: Archytas analis, 
Gonia exul ab, Phorichaeta, Phyto; Sarcophag.: Helicobia 4-setosa ; 
Musc.: Phormia regina, Pseudopyrellia fq; Scatophag.: Scatophaga. 
Lepidoptera (1)—Noctu.: Plusia simplex. 
SALICACEAE 
Populus deltoides (anemophilous).—One visitor observed, 
April 14. 
Long-tongued Bees (1)—Ap.: Apis ¢, ab. 
Populus tremuloides (anemophilous).—One visitor observed, 
April 6. 
Long-tongued Bees (1)—Ap.: Apis ¢, ab. 
Salix amygdaloides.—Blooms April 4~May 9; 97 visitors ob- 
served, April 10-28; Mis, Y. 
On staminate flowers: 
Long-tongued Bees (4)—Ceratin.: Ceratina ¢, Zaodontomerus 
do; Nomad.: Heminomada 9, Nomada sayi ¢. 
Short-tongued Bees (13)—Halict. (2): Chloralictus illinoensis, 
Evylaeus arcuatus sc, fq, truncatus sc, Oxystoglossa confusa se; 
Sphecodini: Sphecodium cressonii; Collet.: Colletes inaequalis ¢ 
9, sc; Andren.: Andrena illinoensis ¢ 2, se, fq, pruni 9, salicacea 9, 
se, salictaria 2, sc, Opandrena personata 4, Trachandrena crataegi 
d, nuda Q, se. 
Other Hymenoptera (2)—Vesp.: Vespula germanica; Pompil.: 
Cryptocheilus conicus. 
Diptera (8)—Syrph.: Chrysogaster ontario, Helophilus lati- 
frons, Psilota, Tropidia mamillata, Xylota fraudulosa; Empid.: 
Rhamphomyia irregularis; Bombyli.: Bombylius major; Muse.: 
Morellia. 
On staminate and pistillate flowers: 
Long-tongued Bees (7)—Ap.: Apis se, ab; Nomad.: Gnathias 
cuneatus ¢ 9, fq, ovatus ¢ 9, fq, Nomada denticulata ¢ 9, ab, 
illinoensis ¢ 9, ab, Phor ¢, ab, Xanthidium luteolum ¢ 9, fq. 
