Native Bee Nesting Sites

With 1,600 species of native Bee described and potentially another 1,000 yet to be described, the concept of the ‘Bee hotel’ only goes to demonstrate our collective ignorance of the Epifamily Anthophila, and in a broader sense, that of the Order Insects.

There are only 386 species of Mammal in Australia and it would seem foolish to create a ‘Mammal hotel’ in the hopes of attracting various Mammals. We recognise that each individual Mammal species has different needs and attempts to assist these species require a considerable knowledge of their needs, careful planning, application, maintenance and monitoring. Recognition of this with regard to Bird species has seen the traditional generic ‘bird boxes’ replaced with specialised boxes designed to meet the needs of individual species, and maintenance / monitoring services being made available.

The concept of the ‘Bee hotel’ can go a long way toward educating the public that Bees, and Insects in general, are an important part of an ecosystem and worth dedicating time and effort to conserve. But as with Mammals and Birds, to have functional benefits artificial nesting sites need to be tailored to the specific needs of the target species. (Note, target species. Not target Genus or Family). Given that we are far from even having a description of all Australian Bee species, knowledge of the needs and preferences of each species is practically non-existent. So while we wait for the massively underfunded and underappreciated taxonomists and specialists to do their research, the best we can do for most species is a little trial and error.

As part of my efforts to discover the species that call my backyard home (or at least visit for a feed), I’ve worked towards artificially increasing the biodiversity, in particular Invertebrate biodiversity, above that which might have occurred on the land prior to its conversion to suburbia. The next step in this process is the introduction of artificial nesting sites for the Bees and their associated parasitoid Wasps.

First, I need to know which species actually occur locally. There’s very little value in establishing suitable nesting sites for species like the Green Carpenter Bee (Xylocopa aerata) given that it no longer exists on mainland South Australia. In three years of informal observations on the property, it seems I’ve neglected making observations during the warmer parts of the day. As such I only have 7 Bee records on the property, covering 5 species (excluding the introduced Honey Bee), with 4 Plant associations. Masked Bees (Hylaeus sp.) which nest in wood holes or pithy stems, Blue Banded Bees (Amegilla sp.), which nest in the ground in separate nests (often communally), and two Metallic Sweat Bees (Lasioglossum sp.), which nest in the ground, often with many females per nest.

Autumn is hardly the best time of year to attempt to expand this list. (Although this Metallic Sweat Bee seems to be enjoying the last of the Wahlenbergia stricta flowers). So my best option at this time is to take a broad approach, establishing numerous generic nesting sites over the cool months, targeting the Bee Genera present in this region rather than individual species. Come Spring & Summer some species may make use of these sites. From there I can refine the designs to meet the needs of those local species, and make the nesting sites a more permanent fixture on the property.

An early attempt has already been made by preparing an old Golden Wattle (Acacia pycnantha) trunk with drilled holes of various sizes for utilisation by those Bee species that nest in wood i.e. Resin, Leafcutter, Reed, and Masked Bees. The trunk measures 15cm in diameter, so drilled holes are 12cm to 14cm deep. Hole diameters run from 3mm to 10mm, ranging from a height from the ground of 750mm to 1070mm. Holes face roughly North-East and are in a full sun location.

Either by coincidence alone, or perhaps some ability to smell timber being damaged, a small wasp was observed to fly around the trunk and enter several of the drilled holes, during the drilling process. A promising sign that the holes may provide some benefit.

The site was prepared on 26/03/2022 and is checked regularly. Although it was expected that the site wouldn’t be utilised until Spring, the first hole was in use within 14 to 19 days. It was also expected that without actual observation of the adult, the exact species wouldn’t be known. As luck would have it the hole entrance was filled with a quite distinct cellophane-like material of design known to be associated with the Common Wasp-mimic Bee (Hyleoides concinna). The hole utilised was B1 (8mm diameter, 1050mm high).

During one check of the site, hole A1 (10mm diameter, 1070mm high) was found to contain a juvenile Huntsman Spider.

On the 23/04/2022 (Day 28), it was found that hole B2 (8mm diameter, 955mm high) had also been utilised by the Common Wasp-mimic Bee (Hyleoides concinna).

On the 28/04/2022 (Day 33), it was found that hole A1 (10mm diameter, 1070mm high) had been utilised, again by the Common Wasp-mimic Bee (Hyleoides concinna) with a spoke shaped entrance of cellophane-like material. The adult was currently occupying the nest, at rest with antennae protruding through the entrance material, and retreating deeper when disturbed, only to return to the original position within a few seconds.

In 3 years of casual observations on the property recording over 3,400 observations across 600 species, the Common Wasp-mimic Bee (Hyleoides concinna) had never been recorded. The quick uptake of the nesting site may indicate a demand for such sites in this suburban area.

The order of occupation starting with the higher two 8mm diameter holes (of the four drilled), then the highest 10mm diameter hole (of the four drilled), may suggest a preference for higher nesting sites even if the diameter is larger, i.e. ignoring the 8mm holes at 875mm and 790mm high, and taking the 10mm hole at 1070mm high.

This early success provides an opportunity to utilise the knowledge of the Common Wasp-mimic Bee nesting preferences to establish more permanent sites for this species across the property after the cool season. But for other species, a season of trials will be needed. These will take the form of mud bricks for Blue Banded Bees and various drilled wood for any Resin, Leafcutter, Reed, and Masked Bees. As yet none of these have been observed on the property, but hopefully like the Wasp-mimic Bee these are present in the local environment. (For the time being, ground nesting bees will be neglected). Once local species and their nesting preferences are identified, plans can be made for more permanent and dedicated nesting sites on the property.