Let take a look at Dream Symbols from Ih to Iz.

Illness, sickness : 1. Feeling uneasy and uncomfortable.

Incest : Related to the denied aspects of self. Possibly denotes a desire or in the  process of integrating that denied aspect.

Insanity : 1. Possible indicative of feeling not being able to cope with something.
2. Trying to avoid some responsibility.

Insecticide : 1.Possible associated with wanton destruction and lack of regard for others.
2. May indicate a wish to resolve or overcome some irritating or frustating matters.

Insects : Insects are dream symbols associated with small minor things in life. Often associated with minor frustrations or annoyance that are bugging oneself.

Invisible Presence : Possibly indicative of an aspect of self that is still not fully  known to the conscious personality of the dreamer.

Island : 1. A possible symbol of loneliness.

2. A possible desire to isolate oneself from others. This could be due to facing too much problems.
3. Feeling stuck and clueless.