Chompy!: Article by Tyson Ehlers and Rhia Mackenzie. Photos by Tyson Ehlers.

Photo T. Ehlers

Giant Water Bugs aka Toe-biters are in the family Belostomatidae but we like to call them Chompy, the name my 10 year-old son gave one that he kept as a pet.

It was early winter and my son and his friend were doing what little boys who live around here should do- they were exploring the frozen ponds down at the river when they came across a giant water bug partially frozen in the ice. They brought it home and set up an aquarium and we were amazed to watch this huge insect come to life. Chompy lived up to his name:  a fierce predator, he would lie in wait for a small fish to swim by then aggressively lunge out and grasp his prey with his large forearms. A needle like mouth (rostrum) injects toxic enzymes into the prey and the digested insides are sucked out. You can’t make this stuff up! We fed Chompy small fish, but they will also prey on amphibians, snails, crustaceans and other invertebrates.

Rhia MacKenzie sampling macroinvertebrates

Darcie Quamme is leading the benthic invertebrate sampling program¹ and she has encountered giant water bugs in many of the wetlands in the SWAMP study area. They are surprisingly common, turning up frequently in the kick net.

The basic procedure is to sample invertebrates using a dip the net in and around the emergent vegetation over a set distance and time. Critters are filtered out into a small clear container affixed to the net. The contents are emptied into a sorting tray and it is always     exciting to see a Chompy turn up in the sample.

Belostomatidae

There are over 100 species worldwide, some reaching up to 150 mm long. They are “true bugs” within the order Hemiptera  (related to stink bugs). Apparently only members of the subfamily Belostomatinae show parental care in which the eggs and developing larvae are carried on the male’s back.

These bugs are also known as toe-biters because they can inflict an extremely painful bite. When threatened they will often play dead, emit a foul gas from their anus and can suddenly ‘recover’ and bite the offending threat.

Chompy in goldfish bowl positioned to use breathing tube

Adult giant water bugs breathe through a tube that projects out the rear of their abdomen, and they often lie in wait for prey with just the tube projecting out of the water.  They can fly as we learned with our pet Chompy. One day he disappeared from his aquarium and later turned up under the sofa. If you do keep one as a pet, you need to have a lid on the tank!

Darcie Quamme sampling for macroinvertebrates

¹

The Canadian Aquatic Biomonitoring Network (CABIN) under Environment Canada provides a standardized sampling protocol used to assess the health of streams.  CABIN uses methods that result in comparable, and scientifically credible biological assessments of streams. Water quality and other meta-data are also collected along with the diversity and abundance of benthic “bottom-living”) invertebrates (animals with no backbone).

Screening sample

Darcie Quamme in collaboration with Environment Canada is working to develop a standardized biomonitoring protocol for wetlands.  Although wetland protocols exist south of the border this is brand new territory for British Columbia. This is the second year of the sampling program and by the end of the field season Darcie and the SWAMP team will have sampled 24 wetland sites. The data will be analyzed in conjunction with SWAMP wetland ecosystem classification data over the fall and winter and a report will be available in March 2016.