Two-spotted Long-horned Bee

Howdy, BugFans,

The BugLady keeps getting solicitations from a large, national conservation/environmental organization whose message is “Save the Bees.” Alas, the only bees they picture or mention are honey bees. Heaven knows that honey bees are vital pollinators, and they’re certainly facing big challenges, but the same can be said of our (apparently invisible) native bees.

Turns out that the unassuming Two-spotted long-horned bee (Melissodes bimaculatus) (bimaculatus means “two spots”) is a Pollinator Extraordinaire.

But first, the Family Tree. TSLHBs are in the family Apidae – the Cuckoo, Carpenter, Digger, Bumble, and Honey Bees – and in the tribe Eucerini, the Longhorn bees, the most diverse tribe in the family. Eucerini comes from the Greek Eu, meaning “good” or” true” and keras, meaning “horn” and refers to the hefty antennae of the males. There are about 215 species in the tribe in North America, and some bee people think that “The classification within the tribe is rather chaotic,” and that it is “in serious need of a thorough taxonomic overhaul.” On top of that, the species can be hard to tell apart. Many of the Eucerini are specialist feeders, and as such have names like Squash bee or Sunflower bee. They’re important pollinators of sunflower, melon, and squash crops as well as both wild and garden flowers.

Long-horned bees are mid-sized (maybe a half-inch) and hairy, and many have abdomens ringed with yellow or white. Males have longer antennae than females – some antennae may be as long as their bodies or longer – and females have thicker hair on their back legs (all the better to carry pollen with, my dear). They nest in vertical burrows in the ground, and they are solitary bees, but females of many species will tolerate other nests nearby, and males may rest overnight in amazing sleeping aggregations with other males.

There are around 100 species in the genus Melissodes (which means “bee-like”) in the US. They are hairy and “robust” – about half-again the size of a honey bee (males are slimmer than females) – and many have blue or green eyes. Most Melissodes species are specialist feeders, zeroing in on the flowers of a few species or genera in the Aster/Composite family.  They’re most common in the second half of summer and early fall.

Their burrows are about the diameter of a pencil, often with a small mound of dirt around them, and the individual egg chambers are lined with a waxy material and provisioned with a ball of pollen and nectar. Females sleep in their burrows, but males gather with other males, often gripping a plant stalk with their jaws and dangling all night. In some species, males reuse the same “bedroom.” Professor Robbin Thorne, of the University of California, Davis, called these aggregations “Boys’ Night Out.”

TWO-SPOTTED LONG-HORNED BEES (TSLHBs) are found from Ontario and Idaho south to New Mexico and Texas, and east to the Atlantic. They like places with lots of flowers, including prairies and other grasslands, cities, and agricultural fields.

Males are fancy at the front end – except for some pale hairs on their rear set of legs, males are dark, but they have yellow/white hairs on their face (clypeus) above the mandibles and long, reddish antennae. Females are decorated toward the rear of the abdomen with two white spots, but her face is dark, and she has copious long, white hairs (scopae) on her legs. Both are a half-inch-ish long, and she’s a bit larger than he is.

With a few differences, their biography mirrors that of most Melissodes. Males emerge from their natal tunnels first and patrol the flower tops, looking for females. Females emerge and start looking for good nest sites. Where other species prefer to tunnel in flat ground, the TSLHB likes banks and inclines. She provisions a cell, lays an egg in it, seals it off, and starts working on the next cell.  Although the species is common, their nest sites are rarely found (it’s suspected that they nest under bushes). TSLHBs fly in mid-summer, and there’s one generation per year.

Unlike many in their genus, TSLHBs nectar at and females collect pollen from a wide variety of plants – wildflowers, garden flowers, “weeds,” and agricultural crops – and they start foraging early in the day. When the BugLady tried to check the full list of their food plants at the Discover Life website, she found this message, “On 16 February, 2025, Discover Life had 6.5 million hits, largely by about two million robots that greatly slowed our service to our human users. We’re trying to get rid of them and get our services back. Sorry.”

Cuckoo bees in the genus Triepeolus find the tunnels of TSLHBs, enter them, and lay eggs in the cells. They are kleptoparasites – their larva will kill the Long-horned bee larva and eat the stored pollen.

Along with honey bees and common eastern bumble bees, TSLHBs are among the top three most important pollinators of cotton, and they also pollinate pumpkins, watermelons, and cucumbers.

According to the Tufts Pollinator Initiative, researchers have found TSLHBs on the male flowers of corn plants. Pollen provides insects with fats, protein, carbs, and vitamins, though these ingredients are present in different proportions in different species of flower. But corn is wind pollinated, not insect-pollinated, and insects have little access to the pollen-and-nectar-free female flowers that are found on small, silky ears in mid-stalk. These bees not only like corn pollen, they seem to actively seek it out. In the case of corn, the TSLHB is not a pollinator, it’s a pollen thief!

RABBIT HOLE DU JOUR

Not only do honey bees supply us with bees’ wax and honey, but bee pollination is a highly lucrative traveling show. They pollinate $15 billion worth of crops annually. Starting with the almond crop in California in early spring, hives are trucked around the country – north in spring and summer to pollinate about 125 kinds of nuts, fruits, and vegetables, producing honey as they go, and then back to Texas and Florida where they rest for the winter. It’s called “managed insect pollination,” and it supplements the efforts of the native pollinators (or vice versa). We’re talking tens of thousands of hives on the move, precisely choreographed to be delivered at the right blooming time for each crop. It’s great for the growers, but stressful for the bees.

There are also commercial bumble bee providers, because bumble bees are effective on about two dozen crops, including tomatoes, potatoes, peppers, squashes, clovers (without bumble bees there would be no red clover), sunflowers, and some of the crops that are grown in greenhouses.

As always, the BugLady is pleased to recommend “The ID Guide of Wild Bees – New York” for good information and spectacular pictures.

It’s Invasive Species Awareness Week. 

BOTW will be Missing in Action on Egredior Day (March 4th) (egredior is Latin for “to march forth”), so that the BugLady can have a body part replaced. Catch you later.