Bug Hotel
About a month ago, in March, I made some bug hotels. I started out thinking we only needed one so I would only make one. But then I realised that by the time I made one, I may as well make two or three. So I ended up making three.
I’d never really seen bugs use these things in other people’s gardens. But I liked the concept, and I thought they might be a cool-looking addition to the garden that makes us look really connected with nature etc.
On that basis I went ahead and built them anyway.
What is a bug hotel?
A bug hotel is a little fabricated habitat you place in your garden to provide lots of opportunities for ‘good’ bugs to make a home. They come in various materials, shapes and sizes and can be bought online, in shops like Bunnings or made by hand. YouTube is full of tutorials on how to make them and describing the various features that are going to attract the right type of hotel guests.
A ‘good’ bug can be a wasp, hornet, solitary bee or similar - Any insect that provides a positive function in your garden. ‘Good’ bugs can assist in pollination of vegetables and fruits and can also help control the number of ‘bad’ bugs that would otherwise cause damage to your plants.
Without an enticing bug hotel, good bugs make their home in whatever appropriate nook or cranny they can find. Holes in trees and walls are good. Some bugs seek out exposed locations, others prefer shade and shelter. In urban areas, opportunities for bugs to make a home can be limited. Purpose-made bug hotels can help address this housing shortage.
Here are a few bug hotel examples:
Building a bug hotel
After watching a few YouTube clips on how to build a bug hotel I got a feel for what the good bugs are really after in a hotel design. I then scrummaged around the garden for appropriate construction materials. These hotels were going to be 5-star!
For the outer frame I built a box out of old heat-treated shipping pallet pine. I cut pre-measured lengths on the drop saw and screwed the boxes together with galvanised screws and an impact driver.
We use galvanised screws for most of the stuff we build out of timber. They produce a very solid result, don’t rust, don’t split timber as easily as nails do and, most importantly, allow for modification or disassembly down the track - future tinkering if you will.
We had just lopped some branches off a Callistemon and these formed some great mini logs for the hotel accomodation. In between the Callistemon logs I jammed some twigs and bamboo offcuts.
Everything was cut neat-ish with drop saw or secateurs to match the depth of the box. My 12 year-old son and I then spent the best part of an hour on the cordless drills, making bug holes. Bug holes ranged in size from 2mm Ø (budget accomodation) to 10 mm Ø (presidential suite or similar).
We gave one of the three finished bug hotels to some friends who had pollination issues with fruit and vegetables not setting in their garden. The remaining two bug hotels are now hanging on fences at our place - one in the front yard, one in the back.
Do they work?
Well I was very sceptical as I’d never really witnessed any guests staying at the few store-bought bug hotels that I’d seen. With some complacency I checked ours for guests, roughly weekly. Lo-and-behold! A few of the holes showed signs of occupation as time passed by.
Today the dog and I were out in the garden sunning ourselves against the fence when a noisy wasp drunkenly dipped and swerved around me. I followed it’s path and to my surprise it landed on the bug hotel and ducked into a hole. Just before it disappeared I saw a juicy green caterpillar hanging under it’s belly.
I ran inside and grabbed my camera…
Fifteen minutes later the same wasp returned to the same hole carrying ANOTHER juicy green caterpillar. This time I got a few snaps of it landing then disappearing down the hole. See time-lapse (of sorts) above.
So YES!… Bug hotels do work!
This wasp is actually doing a particularly useful job for us. The juicy green caterpillar it eats is the larvae of the White Cabbage Moth. These caterpillars have been decimating our winter Brassica crop (cabbages, broccoli, brussels sprouts, cauliflower, kale and turnip) and we’ve been struggling to get them under control. We have tried everything from fake white moths (the real moths are territorial) and companion planting (deterrent)’ to home-remedy soap spray and manual caterpillar removal.
Until the wasps came along the only treatment that we got some limited results from was Dipul (certified organic caterpillar control product which can be used on edibles (herbs, vegetables and fruits) and ornamentals) a store-bought bacterial insecticide.
I saw the wasp(?) store a total of three green caterpillars in the one hole. I’m wondering if it will cap-off the hole soon, in the same way some other holes in the hotel have been closed over. It’s also interesting to note that there are quite a few White Cabbage Moths still
What type of wasp is that?
With a little help from the Retrosuburbia Facebook page the wasp is identified as an Australian hornet (Abispa ephippium). Also known as a Potter Wasp. The closest visual correlation that I can make is a Black-headed Mud-nesting Wasp. Hymenoptera > Vespidae > Pseudabispa or Epiodynerus sp.
Below is a reference describing Potter Wasp features and habitat from the Project Noah website.
‘The Australian Hornet (aka Potter Wasp) is quite large - approx. 30 mm. The abdomen is orange and black, and the thorax is black with orange triangle at the shoulders. The antenna and legs are orange-yellow. They are solitary and build a mud pot-shaped nest attached to a tree trunk or side of a building. They can sting but are not aggressive.
Often seen in gardens searching for caterpillars on leaves on trees and shrubs, or collecting mud from damp soil or roof gutters.’
Potter wasps make mud nests for their eggs and larvae or use abandoned burrows of other insects. They stock the nests with caterpillars and other grubs, which they seal in with mud. These are eaten alive by the wasp larvae. (Reference)
Post script
Saw another little black fly-like insect checking in to the hotel today. I’m hoping it might be a Hyaleus Delicatus.
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Written by Adam, April 2020