SB 3.31.27

tudanty āma-tvacaṁ daṁśā
 maśakā matkuṇādayaḥ
rudantaṁ vigata-jñānaṁ
 kṛmayaḥ kṛmikaṁ yathā
Synonyms: 
tudanti — they bite; āma-tvacam — the baby, whose skin is soft; daṁśāḥ — gnats; maśakāḥ — mosquitoes; matkuṇa — bugs; ādayaḥ — and other creatures; rudantam — crying; vigata — deprived of; jñānam — wisdom; kṛmayaḥ — worms; kṛmikam — a worm; yathā — just as.
Translation: 
In his helpless condition, gnats, mosquitoes, bugs and other germs bite the baby, whose skin is tender, just as smaller worms bite a big worm. The child, deprived of his wisdom, cries bitterly.
Purport: 

The word vigata jñānam means that the spiritual knowledge which the child developed in the abdomen is already lost to the spell of māyā. Owing to various kinds of disturbances and to being out of the abdomen, the child cannot remember what he was thinking of for his salvation. It is assumed that even if a person acquires some spiritually uplifting knowledge, circumstantially he is prone to forget it. Not only children but also elderly persons should be very careful to protect their sense of Kṛṣṇa consciousness and avoid unfavorable circumstances so that they may not forget their prime duty.