• Insects reach seeds through cracks on the soil surface.Jupiterimages/Photos.com/Getty Images
  
  When you plant vegetable garden seeds directly outdoors, there's always the risk the seed won't germinate because of insect damage. Seedcorn beetles, wireworms and thief ants are among the insects that damage and kill seeds ready for germination underground. Corn, beets and beans are among the crops insects feed on every planting season.
  
  

Corn

• Cold, wet weather invites pests to your cornfield.corn-cobs image by Maria Brzostowska from Fotolia.com
  
  Corn seeds often become fodder for seedcorn maggots, especially during rainy and cold springs. The insects have the potential to destroy entire seeded fields. The season's first generation of seedcorn maggots appears in May and the last one in August, with about three more generations hatching from eggs between those months. Wireworms, six-legged hard-shelled insects, also feed on corn seeds underground.
  
  

Beets

• If your beet seeds don't germinate, you might have soil insects.early red beets and young beet leaves image by Maria Brzostowska from Fotolia.com
  
  A number of sown seeds, including beets, become wireworm feed every planting season. The insects eat the beet embryos, leaving the seed shells hollow. The lygus bug is another insect that feasts on beet seeds. The bug is only ¼ inch long and green or brown. If you plant beets next to another field with a lygus bug infestation, the insects promptly move to your side to start gorging on your beet seeds.
  
  

Snap Beans

• Seedcorn maggots burrow into snap beans sown underground, destroying their embryos. Severe infestations of seedcorn maggots are more common in soils amended with manure and during wet springs. The temperature also plays a role in their appearance, as they require a range from 45 to 75 degrees Fahrenheit to thrive.
  
  

Spinach

• Healthy spinach leaves signify your soil is pest-free.spinach image by ivan kmit from Fotolia.com
  
  Spinach seeds often don't have a chance to grow into plants because of springtail infestations in the seedbed. Springtails are small white insects that live in the ground and move slowly. Their destruction can be colossal, as they're capable of wiping out and weakening an entire field of spinach seeds.
  
  

Onion

• You might have to resort to pesticides to prevent onion maggots.onion image by Zbigniew Nowak from Fotolia.com
  
  An onion seed nemesis is the onion maggot, the white larva of a gray fly ¼ inch long. These maggots not only feed on onion seeds, they also eat mature onion bulbs, either keeping your onion stand from taking off or damaging your crop just before harvest.