Pest Weather 

For New Zealand’s North Island and Upper South Island December was amongst the wettest on record. January has begun in a similar vein and the pattern is set to continue for the first two of weeks of 2012. The wet weather is influencing the levels of many pests in homes. Pests, some of which would not normally be regarded as a problem, benefit from the warm wet conditions and have a population explosion. Some have spread their way indoors where they cause concern to occupants.

Kiwicare Technical Manager, David Brittain says “We have had several enquiries about small shrimp or flea like creatures swarming into people’s houses. They are Gammarus sand hoppers, small crustaceans that are usually found on the beach or in the garden. The wet weather has allowed their population to grow and spread. They don’t cause any harm but those affected can be unsure of what they are and whether to be concerned.”

More common insect pests such as cockroaches also thrive in moist humid conditions. They normally have to hide in cracks and crevices to keep from drying out during hot dry summers, but with the recent wet conditions, they are able to travel from building to building more easily. It is likely that people will encounter many new cockroach infestations this summer.

Flies breed in decaying animal and vegetable matter and as decay is accelerated and flies survive longer in warm moist conditions, fly numbers are consequently well above normal.  Kiwicare is seeing a significant increase in sales of fly control products; surface sprays and baits for giving homes a season-long fly proofing.

However, the wet weather is not all bad news. Some pest numbers are reduced in these conditions. Ants in places where heavy rain has caused flooding are drowned out of nests and when the water recedes the ants must put their energy into rebuilding the nest before beginning breeding again. Wasp numbers are likely to be reduced this year compared to the high levels of last year. Wasp nests can be affected by flooding and a proportion of their food comes from the honeydew produced by sap-sucking scale insects. The honeydew gets washed away in wet weather and so wasps will have had less food so far this year, keeping the population lower.

NIWA and the Met Service are still predicting that warmer drier weather in February is possible and if this happens it may still change the range of pests and diseases we will be fighting around our homes and gardens for the second half of summer.

David Brittain
Kiwicare