According to observations of naturalists and beekeepers.
Where are you?
SOURCE FOR HONEY BEES:
Minor in most areas
Catalpa speciosa is a species of Catalpa native to the midwestern United States. Catalpa speciosa was originally thought to be native only to a small area of the midwestern United States near the confluence of the Mississippi and Ohio Rivers. Today, its range has widely expanded east of the Rocky Mountains outside of its restricted pre-settlement location, further obscuring the true native range.
This plant is present in at least 40 states/provinces in this country.
It is a medium-sized, deciduous tree growing to 15–30 meters tall and 12 meters wide. It has a trunk up to 1 m diameter, with brown to gray bark maturing into hard plates or ridges.
The leaves are deciduous, opposite (or whorled), large, heart-shaped, 20–30 cm long and 15–20 cm broad, pointed at the tip and softly hairy beneath. The leaves generally do not color in autumn before falling, instead, they either fall abruptly after the first hard freeze or turn a slightly yellow-brown before dropping off. The catalpa tree is the last tree to grow leaves in the spring. The winter twigs of northern catalpa are like those of few other trees, having sunken leaf scars that resemble suction cups. Their whorled arrangement (three scars per node) around the twigs is another diagnostic.
The flowers are 3–6 cm across, trumpet-shaped, white with yellow stripes and purple spots inside; they grow in panicles of 10-30.
The fruit is a long, thin legume-like pod, 20–40 cm long and 10–12 mm diameter; it often stays attached to a tree during winter (and can be mistaken for brown icicles). The pod contains numerous flat, light brown seeds with two papery wings.
The blooming period occurs from late spring to early summer, lasting about 2 weeks. Individual flowers remain in bloom for only a short time; they have a pleasant fragrance.
Afterward, fertile flowers are replaced by narrowly cylindrical seedpods that are 10-18" in length and about ½" across; they are either straight or slightly curved and droop downward from short stalks. Immature seed pods are green, while mature seedpods are dark brown.
Cercis canadensis (aka: Eastern redbud, Redbud, Cersis Reniformis)
Acer saccharinum (aka: Silver maple, Soft maple)
Pyrus communis (aka: European pear, Common pear)
Celtis laevigata (aka: Hackberry, Sugarberry, Lowland hackberry, Sugar hackberry, Arizona sugarberry, Netleaf hackberry, Small's hackberry, Southern hackberry, Texas sugarberry)
Acer negundo (aka: Boxelder, Western boxelder, Arizona boxelder, California boxelder, Texas boxelder, Interior boxelder, Violet boxelder)
Salix nigra (aka: Black willow, Swamp willow, Southwestern black willow, Gulf black willow, Scythe-leaved willow)
Salix lucida (aka: Shining willow, Greenleaf willow, Tail-leaf willow, Whiplash willow, Pacific willow, Lance-leaf willow, Longleaf willow, Red willow, Western shining willow)
Amelanchier arborea (aka: Common serviceberry, Downy serviceberry, Juneberry, Shadbush, Shadblow, Sugarplum)
Malus domestica (aka: Pyrus pumila, Malus pumila, Apple)
Prunus cerasus (aka: Sour cherry, Tart cherry, Dwarf cherry, Montmorency cherry)
Acer saccharum (aka: Sugar maple, Rock maple, Hard maple)
Malus coronaria (aka: Sweet crab apple, Garland crab, Alabama crab, Allegheny crab, American crab, Baltimore crab apple, Buncombe crab, Dawson crab, Dunbar crab, Fragrant crab, Garland tree, Lanceleaf crab apple, Missouri crab, Sweet-scented crab, Sweet wild crab, Wild crab, Wild sweet crab, Wild Crab Apple)
Prunus americana (aka: American plum, Goose plum, River plum, Wild plum)
Salix exigua (aka: Narrowleaf willow, Coyote willow)
Prunus pumila (aka: Sandcherry, Western sandcherry, Eastern sandcherry, Great Lakes sandcherry)
Celtis occidentalis (aka: Common hackberry, Bastard elm, Nettle-tree, Northern hackberry)
Salix lutea (aka: Yellow willow)
Salix amygdaloides (aka: Peachleaf willow, Peach leaf willow)
Malus ioensis (aka: Bechel crab, Crab apple, Iowa crab, Iowa crab apple, Prairie crab, Prairie crab apple)
Ajuga reptans (aka: Bugle, Blue bugle, Bugleherb, Bugleweed, Carpetweed, Carpet bugleweed, Common bugle, St. Lawrence plant)
Rhamnus cathartica (aka: Common buckthorn, European buckthorn, Dahurian buckthorn)
Robinia pseudoacacia (aka: Black locust, False acacia, Yellow locust, White locust, Green locust, Post locust, Falsa acacia, Robinia)
Catalpa speciosa (aka: Northern catalpa, Hardy catalpa, Western catalpa, Cigar tree, Catawba-tree, Bois chavanon)
Astragalus (aka: Milkvetch, Locoweed, Goat's-thorn)
Rhus glabra (aka: Smooth sumac, Common sumac, Rocky Mountain sumac, Red sumac, Western sumac, White sumac)
Brassica napus (aka: Rapeseed)
Sinapis arvensis (aka: Charlock mustard, California rape, Charlock, Corn mustard, Canola, Kaber mustard, Rapeseed mustard)
Gleditsia triacanthos (aka: Honey locust, Honey shucks locust, Common honeylocust, Sweet bean locust)
Prunus serotina (aka: Black cherry, Wild black cherry, Rum cherry, Mountain black cherry, Wild cherry)
Asclepias tuberosa (aka: Butterflyweed, Butterfly Milkweed, Orange Milkweed, Pleurisy Root, Chigger Flower, Canada root, Fluxroot, Indian paintbrush, Indian posy, Orange root, Orange Swallow-wort, Tuber root, Yellow milkweed, White-root, Windroot, Butterfly love)
Tilia americana (aka: American basswood, Basswood, Linden)