This article is from the Children Allergies and Asthma FAQ, by Eileen Kupstas Soo email@example.com with numerous contributions by others.
Wasps, honey bees, hornets, yellow jackets and ants are the insects
most likely to cause strong allergic reactions. Some biting insects
(mosquitoes, flies, lice, kissing bugs and fleas) can cause allergies
as well because they inject saliva to thin the blood when they
bite. Finally, some caterpillars are covered with hairs that
contain a substance irritating to human skin and this can sometimes
cause allergic reactions. Less commonly, insects or insects parts
can cause allergic reactions when they are inhaled or swallowed.
Different insect species' venom has different potential allergens.
This means that a person who is strongly allergic to wasps may not be
allergic to yellow jackets at all and may be only mildly allergic to
honeybees, or vice versa.