It is recommended that you do this solo, or with a group of friends that is taking turns getting this achievement. Items appear as small open trash bags or green containers on the ground of random areas. They are usually well hidden. Make sure to search areas for items before placing the drill, as enemies will only spawn once drilling starts.
Sweep through all 3 areas as much as possible, and make sure to look through every corner of the map before moving on to the next zone. After clearing the final hive, you will have unlimited time to explore as long as you don't plant the bomb, so it is recommended that you do this if playing with others.
Here is a video that will show all the most common spawn points of items:
Scouts = grey coloured aliens, the starting aliens Scorpions = yellow coloured aliens, they are very acrobatic Lepers = red coloured aliens, bigger than scouts Rhinos = the ones with the armored plated body, hard to kill
@3 a random enemy that spawns for the challenge but isnt marked in a special way
@4 it goes scouts-the little guys from the start scorpions-the guys that throw balls of acid hunters-the big version of the scout seeker-the bomb scouts that spawn from the meteorites rhinos-the big mothers that are heavily armored and hard to kill
Just some advice, I did this and the trap achievement on my first attempt in one try, Start a solo match and activate every trap and try to complete challenges to make the game easier further on, When you spawn there is usually to scavenge options next to you, And just look in every corner and house before you love on, Don't place the drill until you're certain there are no more, By the end I think I had 46 and left.
It is very EASY! Play solo… Finish Area one first then don't drill in one of hive in Area 2. You have unlimited time to collect trashes in both Area 1 and 2. I got exact, 40 trashes in both areas, 25 in first area and 15 in second area. Sometimes not all 40 there, if you fail, try again. At least few tries or less, you should be able to collect 40 without entering third area.
Escaped the 1st & 2nd once got the season pass. Looking for help getting this achievement and some of the others in extinction. Any interested my gamertag is ilL W1ll 313. Add me will be online Monday Wednesday &Thursday.