Pests I have known

At least - pests I got to know this year. 

Aphids and Whitefly

Aphids are very small soft-bodied insects, and I've seen green, white, yellowish, black, and brown aphids in my garden.  They will congregate on young stems and leaves, beneath older leaves, and often on flower buds and young fruit.  They penetrate the plant tissues with their mouth to feed on them.  An interesting fact is that they secrete a sweet sticky substance that some kinds of ants like to feed on.  The ants like the stuff so much that sometimes they will carry the otherwise slow-moving aphids up onto plants and place them there to return and harvest their secretions! 

Being small, aphids will usually not cause significant damage unless they occur in very large numbers.  They can be easily dislodged from plants using a water hose (make sure you aim the hose upwards to get them from underneath leaves).  They are also easily controlled with horticultural oil, which can be made at home (I'll let you Google to find what sounds like your favorite recipe).  Ladybugs LOVE aphids, and so do Preying/Praying Mantises.  Welcome both into your garden! 

Whitefly are similar in habits to aphids, only my experience has been that they can take over and more quickly cause real trouble in your garden.  They can be controlled with horticultural oil but application is trickier since they will fly off the plant at first hint of trouble, making it difficult to douse them efficiently.   On the plant they may look like a soft moldy substance, but upon gentle agitation of leaves they'll fly up all over the place and in your face. 

A byproduct of an infestation of aphids, and also of whitefly, is something called sooty mold.  Like aphids, whitefly secrete a sweet sticky substance.  Should enough of that stickiness remain on your plants for long enough, sooty mold can begin to grow within the sticky stuff on your plants.  It is very black and almost looks like somebody spray painted your plants.  The sooty mold will often do more damage than the aphids or whitefly themselves, as it blocks out light and oxygen from reaching plant cells.  Prune off effected plant parts and destroy them far away from your garden.  Don't add them to your compost pile.  Then get rid of the aphids or whitefly. 

In my garden this year I had a few aphids here and there, mainly on the squash flowers and substantially on the tenderest growth of my okra plants.  I did see the ants helping them out on the okra.  They were not enough of a problem for me to do much other than spray them off the plants as I watered each time.  Whitefly showed up more recently, but as my summer garden was already in decline, I've not given them any attention.  Since cleaning out the garden in preparation for some fall planting, I've not noticed the whitefly at all.  They do need host plants to be close together in order to thrive. 

Leaf Miners and Vine Borers

You know you have leaf miners when you see their tracks on the leaves of squash, cucumber, and sometimes tomatoes or peppers.  They are pretty harmless - I've never had trouble enough with them to warrant any treatment; they generally don't do enough damage to enough leaves to significantly set the plant back. 

You know you have vine borers when a leaf and stem on your squash plant wilts and turns yellow, then brown.  I'm not including a photo of the borer itself as you won't see them unless you cut off the affected stem, slice it open, and find the disgusting-looking grub slithering about inside.  Since they hide out underground until they bore into thick stems for their sustenance, they are very difficult to control.  The best non-chemical method is to be vigilant, and as soon as you see a leaf beginning to wilt, do as described above and stomp the life out of the buggers. 

Squash Bugs
The photo here shows an immature squash bug - a smaller, round grey version of the adult - which are larger, more elongated, and brown - almost blackish in color.  They can be confused with stink bugs, but are not quite the same insect.  Some varieties have long angular legs and can look quite scary. 

I had few of these in my main garden plot, but I believe a large infestation of them to be the cause of the sudden and complete death of all butternut and acorn squash in my compost garden. They will congregate in large numbers on the central stems, vines, leaves, and fruit of squash plants, and sometimes cucumbers.  At first they appeared to be causing no real damage, but they seemed to launch a sudden and complete attack on the plants all at once, sucking the life out of them.  Literally my plants were green one day and wilted, yellow, and browning the next.  Next year I will not tolerate these curious-looking insects in my garden.  They are very easy to step on, and if that doesn't work next year I'll look up what other methods can be used to eradicate them. 

Deer

Yes, deer.  We've got plenty in the area, and although I have not actually seen any in our yard for several years, the half-eaten apples under the apple tree are plenty suspicious.  I went out to the garden one morning to find the 3 okra plants on the end were completely defoliated.  They were already several feet tall and so I knew it could not have been rabbits.  It was too much damage to happen over one night to think it was some sort of insect, and the remaining bits of leaves had very obviously been chomped, not nibbled.  Those 3 plants were located right along any path that would be taken to the apple tree, and so I feel pretty good about my conclusion.

Other than the loss of those squash plants here at the end of the season and the deer keeping 3 okra plants pruned beyond production, there was no other significant damage from pests and I used no control methods other than spraying them off.  Once again I'm convinced that healthy plants and a well-maintained garden are a wonderful pest preventative.  At the end of the season I slacked on weeding and I noticed several new potential pests here and there - it became obvious to me that weeds are an exceptional place for pests to live, hide, and breed within your garden.