[Subversive_plot]

Recently I noticed tan-colored aphids on some of my tomato plants.  My entomologist son was coming over for dinner, and I told him about the aphids, and asked how he would treat them, consistent with integrated pest management practices. He said don't do anything yet, they may be beneficial!

When he got to the house, he looked at the aphids, his suspicion was confirmed.  The aphids had been parasitized by Aphidius wasps!  See https://bugoftheweek.com/blog/2020/5/25/whats-up-when-aphids-have-a-hole-in-their-rear-end-tiny-parasitic-wasps-aphidius-spp .  They lay eggs in the aphids, eventually killing them, but producing many more tiny wasps that will control future generations of aphids (not to worry, the wasps are tiny, not a danger to humans).

A related wasp lives in the UK.  If you see motionless tan aphids on crops, look for a hole in them before spraying with anything.  They could be the best friend in your garden to get rid of aphids.

Edited to change the word "wasps" to the correct word 'aphids' in the paragraph above.

[Nobbie]

 I think your eyesight is a lot better than mine. I can barely see the aphids, let alone holes in them

[Subversive_plot]

I think your eyesight is a lot better than mine. I can barely see the aphids, let alone holes in them

My eyesight isn't what it used to be!     Fortunately (or unfortunately, depending on your POV  ), I'm a geologist, and keeping assorted and various hand lenses in every desk drawer or tool box is sort of an occupational hazard.  A decent magnifying glass for reading will do, and I use those to look at the tiny bugs so I know what bugs are friend or foe.  For the aphid mummies, if they are tan, and they don't seem to move at all, they are probably aphid mummies (holes visible or not). 

FWIW, I've noted that plants that already have 'mummies' don't seem to have live aphids hanging about.  Same goes for nearby plants.