A home invasion

We have had some good rains in the last two weeks after some 11 months of drought (dry period). In the past 2-3 days we noted some small black caterpillars dangling on their own silk thread or inching up trees. We have seen caterpillars in various colours, forms and sizes before. They are 'instars' (hatched from eggs and growing into final forms) of butterflies (day insects) or moths (night insects). But, we see more and more them today. They are everywhere in wooded areas. They are all over the lawns. They are inching (with their 3 pairs of legs in the front and 2 pairs pf prolegs followed by a pair of claspers at the rear end -- see pictures) up the front doors of the house. They are covering our windows....

We are being invaded by caterpillars -- millions of caterpillars. Why? What bring them out in great number? What are they doing or going to do? Should we report this invasion to authority (for food and forest or environment security  purpose)? Were there incidents like this invasion before and what were the results? Were they as bad as locust swarms that denuded wheat farms in Australia before?

(Note the little horn at segment 4 after the third pair of legs)

We looked up the Net but could not find any exact match. The best clue suggests they may be caterpillars of 'oenochroma vinaria' moths (see wikipedia and http://lepidoptera.butterflyhouse.com.au/chro/vina... ).

Anyone know what they are? How do they impact food, environment and people?

I need to know so I can deal with this "natural" event in the right way.

:-)

NB 1) More pictures of members of the 'vinaria' family (note the 3 pairs of legs, 2 pairs of prolegs at rear, a pair of claspers and a horn on the back at body segment 4, similar spots and markings)

http://lepidoptera.butterflyhouse.com.au/chro/vinarb.jpg
https://www.flickr.com/photos/burtonandy/433576203...

NB 2) Armyworms are more destructive to food production (an outbreak in China 2012 damaged hundreds of millions dollars of food production). See http://en.wikipedia.org/wiki/Mythimna_separata

http://en.wikipedia.org/wiki/File:Mythimna_separata_(catepiller).jpg
http://en.wikipedia.org/wiki/File:Mythimna_separata.png
http://en.wikipedia.org/wiki/File:Mythimna_separata.jpg